JP2020099057A - System and method for srs switching, transmission, and extension - Google Patents

Abstract

To provide a system and a method for SRS switching, transmission, and extension.SOLUTION: In a network 200 for supporting carrier aggregation/switched transmission, a set 240 of aggregated component carriers is assigned to UE 210 for downlink carrier aggregation and/or carrier selection. A base station 220 sends an SRS switch message to cause the UE to send a SRS symbol on any component carrier. The base station signals a periodic SRS setting parameter by a radio resource control (RRC) message to switch the periodic SRS. The base station signals an aperiodic SRS setting parameter in a downlink control indication (DCI) message, and switches the aperiodic SRS.SELECTED DRAWING: Figure 2

Description

[Cross reference to related application]
This patent application is based on U.S. Provisional Application No. 62/317,327 filed April 1, 2016, U.S. Provisional Application No. 62/317,351 filed April 1, 2016, May 13, 2016. US Provisional Application No. 62/336,347 filed, U.S. Provisional Application No. 62/374,527 filed August 12, 2016, U.S. Provisional Application No. 62/378,030 filed August 22, 2016, And US Provisional Application No. 62/401,701, filed September 29, 2016, each of which is incorporated by reference as if reproduced in its entirety.

[Technical field]
The present invention relates to systems and methods for wireless communication, and in particular embodiments to systems and methods for sounding reference signal switching.

Next generation wireless networks need to provide higher throughput to support a higher number of subscribers and applications that require high data rates such as video, high resolution images, and so on. Various techniques have been proposed to increase the overall throughput provided to mobile devices in wireless networks. One such technique is carrier aggregation, which communicates data to and from a mobile device on multiple carriers at the same time, thereby increasing the bandwidth available to the mobile device. Another technique is carrier selection (also called carrier switching), in which existing communication sessions associated with mobile devices are switched from one carrier to another. Carrier selection may increase the available bandwidth available to mobile devices by allowing the communication session to transition to component carriers that exhibit better channel quality.

Technical advantages are generally achieved by the embodiments of this disclosure that describe systems and methods for SRS switching, transmission, and enhancement.

According to an embodiment, a method for reference signal transmission is provided. In this example, it is provided that the method comprises the step of receiving one or more downlink transmissions on the first aggregated component carrier set. The UE may simultaneously transmit uplink signals on less than all component carriers in the first aggregated component carrier set. The method further comprises transmitting sounding reference signal (SRS) symbols on different component carriers in the first aggregated component carrier set during different periods of time. An apparatus for performing the method is also provided.

According to another embodiment, a method for receiving a reference signal is provided. In this example, the method includes transmitting one or more downlink signals to a user equipment (UE) on a first aggregated component carrier set. The UE may not transmit uplink signals simultaneously on all component carriers in the first aggregated component carrier set. The method further includes receiving sounding reference signal (SRS) symbols from the UE on different component carriers in the first aggregated component carrier set during different time periods. An apparatus for performing the method is also provided.

According to another embodiment, a method for transmitting an uplink signal is provided. In this example, the method includes transmitting a first uplink signal in a first subframe on a first component carrier during a first time period. The first uplink signal carries at least a first Sounding Reference Signal (SRS) symbol. The method further includes switching from the first component carrier to the second component carrier according to the SRS switching schedule. Uplink RF frequency alignment delay is associated with switching from the first component carrier to the second component carrier. The method further includes transmitting a second uplink signal in the second subframe on the second component carrier during the second period. The second uplink signal carries at least one of the second SRS symbol and the random access preamble.

According to another embodiment, a method for reference signal switching is provided. In this example, the method includes transmitting a first sounding reference signal (SRS) symbol on the primary component carrier during the first period. The UE that transmitted the SRS symbol is configured to transmit both the second SRS symbol on the secondary component carrier during the second period and the uplink control message on the primary carrier during the second period. Scheduled. This results in scheduling collisions between SRS symbols and uplink control messages. The method does not transmit the second SRS symbol on the secondary component carrier during the second period and transmits the uplink control message on the primary component carrier during the second period when the uplink control message meets the criteria. The method further includes the step of transmitting.

According to another embodiment, a method for transmitting an uplink signal is provided. In this example, the method includes receiving from the base station a control signal indicating that the aggregated set of component carriers is assigned to a timing advance group (TAG). At least the first component carrier assigned to the TAG does not support physical uplink control channel (PUCCH) signaling or physical uplink shared channel (PUSCH) signaling. The method further includes transmitting sounding reference signal (SRS) symbols on the one or more component carriers assigned to the TAG according to a timing advance parameter associated with the TAG.

According to another embodiment, a method for receiving an uplink signal is provided. In this example, the method comprises transmitting downlink signals to the UE on the aggregated set of component carriers, and UE on the first component carrier in the aggregated set of component carriers during a first period of time. Receiving a first Sounding Reference Signal (SRS) symbol from the UE and receiving a second SRS symbol from the UE on the second component carrier in the set of component carriers aggregated during the second time period Including and The second component carrier is different than the first component carrier.

According to another embodiment, a method for transmitting a control signal is provided. In this example, the method includes sending control signals to the UE. The control signal indicates that the aggregated set of component carriers is assigned to a timing advance group (TAG). At least the first component carrier assigned to the TAG does not support physical uplink control channel (PUCCH) signaling and physical uplink shared channel (PUSCH) signaling, and the control signal is associated with the TAG to the UE. Prompts to send a Sounding Reference Signal (SRS) symbol on one or more component carriers assigned to the TAG according to the timing advance parameter.

According to another embodiment, a method for receiving an uplink signal is provided. In this example, the method includes receiving a random access channel (RACH) transmission from a user equipment (UE). RACH transmission does not require grants for physical uplink control channel (PUCCH) resources, and does not request grants for physical uplink shared channel (PUSCH) resources, and requests timing advance for component carriers. To do. The method comprises transmitting a control signal indicating a timing advance for a component carrier to a UE, receiving no PUSCH signaling on the component carrier, and receiving no PUCCH signaling on the component carrier, according to the timing advance. , Receiving one or more Sounding Reference Signal (SRS) symbols from the UE on the component carrier.

According to another embodiment, a method for reference signal transmission is provided. In this example, the method includes reporting the user equipment (UE) component carrier capabilities to a base station and providing information from the base station about a first set of component carriers for one or more downlink receptions. And configuring the UE based on information from the base station for a subset of the first component carriers within the first set of component carriers for one or more uplink transmissions. And steps. The one or more transmissions include at least one of a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH) or a sounding reference signal (SRS) symbol transmission. The UE may simultaneously transmit the uplink signal on all component carriers within the first subset of component carriers. The method does not configure a second subset of component carriers for PUSCH/PUCCH, and eNB for a second subset of component carriers within the first set of component carriers for one or more SRS transmissions. Further comprising configuring the UE based on the information from, and transmitting SRS symbols on different component carriers in the first subset of component carriers and the second subset of component carriers during different time periods.

According to another embodiment, a method for reference signal transmission is provided. In this example, the method includes transmitting a first uplink signal on a first component carrier during a first time period. The first uplink signal carries at least a first Sounding Reference Signal (SRS) symbol. The method comprises switching from a first component carrier to a second component carrier according to a switching parameter for an SRS switching schedule and transmitting a second uplink signal on the second component carrier during a second period. The method further includes a step of performing. The second uplink signal carries at least one of the second SRS symbol and the random access preamble, the transmission occurring after the uplink RF frequency alignment time.

According to another embodiment, a method for reference signal transmission is provided. The method includes receiving one or more downlink transmissions on the aggregated set of component carriers and a first component carrier on the aggregated set of component carriers during a first period of time At least one of the sounding reference signal (SRS) symbols and at least one of the physical uplink shared channel (PUSCH) signal and the physical uplink control channel (PUCCH) signaling. At least one of the parameters for the SRS symbol is generated based on the parameters for the PUSCH. The method does not send any PUSCH and PUCCH signaling on the second component carrier during the second period, and at least on the second component carrier within the set of aggregated component carriers during the second period. The method further comprises transmitting the second SRS symbol. Unlike the first component carrier, the second component carrier does not generate any of the parameters for the SRS symbol based on the parameters for any PUSCH.

For a more complete understanding of the present invention and its advantages, reference is now made to the following description in conjunction with the accompanying drawings.
It is a figure of the wireless-communications network of an example. FIG. 3 is a diagram of a network for supporting SRS switching. It is a figure of a communication sequence of an example for setting up a periodic SRS change schedule. 3 is a flowchart of an example method for transmitting SRS symbols. 6 is a flowchart of an example method for performing channel estimation based on SRS symbols. FIG. 7 is a diagram of an example communication sequence for configuring or otherwise triggering aperiodic SRS symbol transmission. 7 is a flowchart of another example method for transmitting SRS symbols. 6 is a flowchart of another example method for performing channel estimation based on SRS symbols. It is a figure of the communication sequence of the Example for setting the DCI message format relevant to an SRS setting parameter. 6 is a flowchart of yet another example method for transmitting SRS symbols. 7 is a flowchart of yet another example method for performing channel estimation based on SRS symbols. It is a figure of the communication sequence of the Example for assigning an uplink carrier switching setting based on the uplink carrier aggregation capability of UE. 6 is a flowchart of an example method for assigning an uplink carrier switching setting based on a UE's uplink carrier aggregation capability. 3 is a flowchart of an example method for transmitting SRS symbols. FIG. 3 is a diagram of a network for supporting SRS switching. 3 is a flowchart of an example method for transmitting SRS symbols. FIG. 7 is a diagram of transmissions that occur before and immediately after the UE 210 switches from a source component carrier to a target component carrier. FIG. 7 is a diagram of transmissions that occur before and immediately after the UE 210 switches from a source component carrier to a target component carrier. FIG. 5 is a diagram of a frame format of an uplink control message signaling UE uplink and downlink RF frequency alignment delays. 6 is a flow chart of an example method for signaling UE uplink and downlink RF frequency alignment delays. 6 is a flowchart of an example method 2100 for determining UE uplink and downlink RF frequency alignment delays. It is a figure of the communication sequence of the Example for adapting a periodic SRS switching schedule according to the deactivation of a component carrier. 6 is a flow chart of an example method for adapting a periodic SRS switching schedule in response to component carrier deactivation. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. 6 is a flowchart of an example method for finding an SRS command in a control message. 6 is a flowchart of another example method for performing channel estimation based on SRS symbols. FIG. 6 is a diagram of uplink transmissions that occur before and immediately after a UE switches from a source component carrier to a target component carrier. 6 is a flowchart of an example method for puncturing an uplink signal to compensate for uplink RF frequency alignment delay. FIG. 6 is a diagram of transmissions that occur before and immediately after a UE switches from a source component carrier to a target component carrier. 6 is a flowchart of an example method for collision handling during SRS switching. FIG. 3 is a diagram of a network for supporting SRS switching. FIG. 3 is a diagram of a network for supporting SRS switching. FIG. 7 is a diagram of a transmission occurring within a subframe during an SRS switch operation. FIG. 7 is another diagram of a transmission occurring within a subframe during an SRS switching operation. FIG. 6B is yet another diagram of transmissions that occur within a subframe during an SRS switch operation. FIG. 6B is yet another diagram of transmissions that occur within a subframe during an SRS switch operation. FIG. 6B is yet another diagram of transmissions that occur within a subframe during an SRS switch operation. FIG. 6 is a diagram of an example wireless network for supporting carrier aggregation and/or carrier selection. FIG. 6 is a diagram of an example heterogeneous (Heterogeneous, Het-Net) for supporting carrier aggregation and/or carrier selection. FIG. 8 is a Het-Net diagram of another embodiment for supporting carrier aggregation and/or carrier selection. 6 is a flow chart of an example method for performing synchronization and measurement using a reference signal. FIG. 5 is a diagram of a carrier-based SRS switching scheme. FIG. 6 is a diagram of an SRS switching scheme based on another carrier. FIG. 6 is a diagram of a plurality of SRS switching operations and SRS transmissions of an embodiment in one subframe. It is a figure of the SRS switching system based on another carrier. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. The figure of the processing system of an example is shown. 1 shows a diagram of an example transceiver.

The structure, manufacture and use of the embodiments are discussed in detail below. However, it should be appreciated that this disclosure provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific examples discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.

As mentioned above, carrier aggregation and carrier selection are techniques that utilize multiple component carriers to increase the available bandwidth available to a given mobile device. The term "component carrier" as used herein refers to a channel or carrier from a transmitter to a receiver. The terms "carrier", "component carrier", "aggregated carrier" and "aggregated component carrier", "serving cell", "one of PCell or SCell", "one of PCC or SCC" , Are used interchangeably throughout this disclosure.

During carrier selection/aggregation, the mobile device may be assigned a set of aggregated component carriers and the base station may transmit downlink signaling on one or more of these carriers at a given time. You may. The mobile station may need to send sounding reference signal (SRS) symbols on each of the component carriers, which allows the base station to transmit unpaired spectrum, eg, TDD carrier or unlicensed spectrum. A channel estimate for a given component carrier can be generated, especially when channel reciprocity is true, such as communication in the spectrum or high frequency spectrum. Channel estimation may be used to select on which of the component carriers to perform downlink transmission, and to select the parameters used to transmit downlink signals (signaling).

In some scenarios, the UE may use a number of transmit (TX) chains for the UE, or power or PA limits for the UE, or other limits in the RF and/or baseband of the UE, or limits in standard specifications. Therefore, it may not be possible to simultaneously transmit the uplink signaling on all the component carriers in the set of aggregated component carriers assigned to the UE. In such a scenario, the UE may need to perform SRS switching in order to send SRS symbols on all of the component carriers. In particular, the UE transmits SRS symbols on the current component carrier during the initial period, switches from the current component carrier to the target component carrier, and then other SRS symbols on the current carrier during later periods. You may send it. As used herein, the term "current component carrier" refers to the original component carrier that the UE is transitioning to during the SRS switch operation and the term "target component carrier" is used by the UE during the SRS switch operation. The component carrier of the destination is shown.

Aspects of this disclosure provide example signaling techniques, formats and schemes to facilitate SRS switching during carrier aggregation/selection.

The SRS switching technique of the present embodiment is applied in a time division duplexed (TDD) channel, a frequency division duplexed (FDD) channel, or a channel that is both TDD and FDD. It should be recognized that it is good. These embodiments may be used in various commercial systems, such as wireless fiber to X (WTTx) systems and the like.

FIG. 1 shows a network 100 for communicating data. The network 100 includes a UE (or terminal or device or the like) 110 having a coverage area 101, a base station 120, and a backhaul network 130. The base station 120 is a base station, extended base station (eNB), 5G gNB, femto cell, small cell, pico cell, transmission point (transmission point, TP), transmission/reception point (transmission-reception point, TRP) and other radios. Like possible devices, it may include any component capable of providing wireless access, among other things by establishing an uplink (dashed line) and/or downlink (dotted line) connection with UE 110. UE 110 may include any component capable of establishing a wireless connection with base station 120. Backhaul network 130 may be any component or collection of components that allows data to be exchanged between base station 120 and remote ends (not shown). In some embodiments, network 100 may include various other wireless devices such as repeaters, femtocells, etc.

In some situations, a UE assigned a set of aggregated component carriers for a carrier aggregation/switched transmission scheme may have uplink signals on all component carriers within the assigned aggregated set of component carriers. May not be transmitted at the same time. FIG. 2 is a diagram of a network 200 for supporting carrier aggregation/switched transmission. As shown, a UE is assigned a set 240 of aggregated component carriers that includes component carriers 241-249 associated with a base station 220. Each component carrier in the aggregated set of component carriers 240 has a different carrier frequency (or center frequency) (eg, f1, f2,... F9). The labels (f1, f2, ...f5, f6, f7, ...f9) indicate that each of the component carriers 241-249 has a different subcarrier frequency band, but these labels are in the frequency domain. It should be appreciated that this does not mean that these corresponding sub-carrier frequencies are contiguous or otherwise continuous with each other. Different carriers may be in the same band, i.e. in-band CA, or in different bands, i.e. inter-band CA.

UE 210 receives a downlink signal from base station 220 on one or more of component carriers 241-249 in aggregated component carrier set 240 according to a carrier aggregation and/or carrier selection transmission scheme, and The uplink signal may be transmitted to the base station 220. To support carrier aggregation/selection, the base station 220 may need to perform channel estimation periodically or aperiodically based on the SRS symbols calculated on the component carriers 241-249. Channel estimation for determining which of the component carriers 241-249 are used for uplink/downlink data transmission, and the transmission parameters (beamforming or pre-coding) for these uplink/downlink data transmissions. It may be used by the base station 220 to select coding parameters, etc.). It should be appreciated that the channel estimation parameters generated by the base station may be more accurate than the channel estimation parameters generated and fed back by the UE. Therefore, UE 210 may need to transmit SRS symbols 261-269 on component carriers 241-249. In some scenarios, the UE 210 may not be able to simultaneously transmit uplink signaling on all component carriers in the aggregated set of component carriers 240, resulting in the need to perform SRS switching. Good. In other scenarios, one or more carriers within the aggregated component carrier set 240 within the aggregated component carrier set 240 are not configured to support PUSCH/PUCCH transmissions and are configured to support SRS symbol transmissions. Alternatively, other carriers in the aggregated set of component carriers 240 may be configured to support both SRS symbol transmissions and PUSCH/PUCCH transmissions. In such a scenario, UE 210 may need to perform SRS switching in order to transmit SRS symbols periodically or aperiodically on component carriers that do not support PUSCH/PUCCH transmission. Thus, even when the UE 210 can transmit uplink signals simultaneously on all component carriers in the aggregated component carrier set 240, SRS switching may occur, in which case it is associated with SRS switching. There is no need for the uplink RF frequency alignment delay to occur. This scenario is also applicable to other sections of this application, eg, the aggregated set of component carriers illustrated/discussed in the description of FIGS.

Aspects of this disclosure provide example signaling techniques, formats and protocols to facilitate SRS switching during carrier aggregation/selection. In one embodiment, radio resource control (RRC) messages are used to signal periodic SRS configuration parameters/commands to the UE. FIG. 3 shows an example communication sequence 300 for communicating RRC messages to establish a periodic SRS switch schedule. In this example, the base station 220 sends an RRC message 321 to the UE 210 that specifies the periodic SRS switching parameters. UE 210 then uses the periodic SRS switching parameters to set the periodic SRS switching schedule, and according to the periodic SRS switching schedule, SRS symbols on component carrier 341 during different intervals within the sequence of periodic intervals. Send 361, 371, 381. Further, UE 210 transmits SRS symbol 362 on component carrier 342 and SRS symbol 375 on component carrier 345. In this example, SRS symbol 362 is transmitted on component carrier 342 in the middle of transmission of each of SRS symbols 361 and 371 on component carrier 341, and SRS symbol 375 is SRS symbol 371 and 381 on component carrier 341. Are transmitted on the component carrier 345 in the middle of each transmission of. Other examples are possible. SRS symbol 362 may be one of a series of periodic transmissions on component carrier 342. Alternatively, SRS symbols 362 may be aperiodic transmissions on component carriers 342 and on component carriers. Similarly, SRS symbol 375 may either be one of a series of periodic transmissions on component carrier 345 or an aperiodic transmission on component carrier 345. In some examples, the periodic SRS symbol may be referred to as a "trigger type 0 SRS" and the aperiodic SRS symbol may be referred to as a "trigger type 1 SRS". The fact that it is a periodic SRS symbol is that it is generally transmitted according to a periodic schedule, and the fact that a periodic SRS symbol may be referred to as a "trigger type 0 SRS" is a periodic SRS symbol. It should be appreciated that does not mean that it is "triggered" in any way by an aperiodically occurring event (eg, DCI message, etc.). In some embodiments, each component carrier that does not support PUSCH signaling is associated with another component carrier that supports PUSCH signaling for SRS switching operations. In such an embodiment, SRS transmissions may not be allowed on component carriers that support PUSCH signaling during the period when SRS transmissions are performed on component carriers that do not support PUSCH signaling, and vice versa. is there. Techniques for triggering aperiodic SRS symbol transmissions are discussed in more detail below.

As mentioned above, the RRC message 321 carries or otherwise indicates the periodic SRS switching parameters. The periodic SRS switching parameter may be any parameter that can be used to generate or otherwise change the periodic SRS switching schedule, such as the period between consecutive intervals in a sequence of periodic intervals. The RRC message 321 may also specify other SRS parameters. In one example, the RRC message 321 is an orthogonal frequency division multiplexed (OFDM) or subcarrier in a subframe in which the UE transmits SRS symbols or single-carrier frequency-division multiple access (SC-). FDMA) Specify the symbol position. In another example, RRC message 321 specifies the number of SRS symbols and/or SRS transmission parameters to be transmitted during a given interval or series of intervals (eg, transmit power level for SRS symbols, etc.). FIG. 4 is a flowchart of an example method 400 for transmitting SRS symbols according to a periodic SRS switching schedule that may be performed by a UE. In step 410, the UE receives a Radio Resource Control (RRC) message that specifies the periodic SRS configuration parameters. In step 420, the UE sets a periodic SRS switching schedule based on the periodic SRS setting parameters specified by the RRC message. In step 430, the UE transmits SRS symbols on the component carrier during a periodic interval within the sequence of periodic intervals according to the periodic SRS switching schedule.

FIG. 5 is a flowchart of an example method 500 for performing channel estimation according to a periodic SRS switching schedule, which may be performed by a base station. In step 510, the base station sends a Radio Resource Control (RRC) message specifying periodic SRS configuration parameters to the UE. In step 520, the base station receives SRS symbols on the component carrier during the sequence of periodic intervals according to the periodic SRS configuration parameters specified by the RRC message. In step 530, the base station performs channel estimation on the component carrier according to the SRS symbols received on the component carrier.

Downlink Control Information (DCI) messages may also be used to signal SRS configuration parameters/commands to the UE. FIG. 6 illustrates an example communication sequence for communicating DCI messages to specify or indicate transmission parameters (eg, power control parameters) for SRS transmissions, or to trigger aperiodic SRS symbol transmissions. Indicates 600. As shown, the base station 220 sends a DCI message 622 to the UE 210. DCI message 622 specifies SRS configuration parameters. After receiving the DCI message 622, UE 210 transmits SRS symbol 672 on component carrier 642 according to the SRS configuration parameters specified by DCI message 622. The DCI message 622 may be sent on the component carrier 642. Alternatively, DCI message 622 may be sent on a different component carrier.

In one example, DCI message 622 triggers the transmission of SRS symbol 672 on component carrier 642. In such an example, DCI message 622 may be communicated on component carrier 642. Alternatively, the DCI message 622 is on one of the component carriers 641, 645 (eg, on a primary cell or primary component carrier (PCC) configured for PUCCH and/or PUSCH transmission). They may be in communication, in which case DCI message 622 triggers an inter-carrier transmission of SRS symbol 672 on component carrier 642.

DCI message 622 may instruct UE 210 to transmit SRS symbol 672 in the middle of transmission of SRS symbol 671 and SRS symbol 681 on component carrier 641. For example, UE 210 may be transmitting SRS symbols 661, 671, 681 on component carrier 641 according to a periodic SRS switching schedule, and DCI message 622 may be periodic to UE 210 on component carrier 641. In the middle of the transmission, it may be instructed to perform an aperiodic SRS transmission on the component carrier 642. Thus, the DCI message 622, to the UE 210, switches from component carrier 641 to component carrier 642 after transmission of SRS symbol 671, transmits SRS symbol 672 on component carrier 642, and then to component carrier 641. It may be prompted to switch back, so that the SRS symbol 681 can be transmitted during the next available periodic interval. This depends on whether the UE 210's uplink radio frequency (RF) frequency alignment delay allows the UE 210 to perform SRS switching operations in the middle of consecutive periodic intervals. The transmission of SRS symbols 681 at intervals may or may not be delayed. The DCI message 622 may indicate other types of SRS configuration parameters instead of (or in addition to) triggering aperiodic SRS transmissions. For example, DCI message 622 may specify transmission parameters for SRS symbols 672, such as SRS transmission power level.

FIG. 7 is a flowchart of an example method 700 for performing an aperiodic SRS transmission that may be performed by a UE. In step 710, the UE monitors a physical downlink control channel (PDCCH) for a downlink control information (DCI) message. In step 720, the UE detects a DCI message specifying SRS configuration parameters. In step 730, the UE transmits the SRS symbol on the component carrier according to the SRS configuration parameter specified by the DCI message.

FIG. 8 is a flowchart of an example method 800 for performing channel estimation according to an aperiodic SRS transmission, which may be performed by a base station. In step 810, the base station sends a downlink control information (DCI) message that specifies SRS configuration parameters to the UE. In step 820, the base station receives SRS symbols on the component carriers according to the SRS configuration parameters. In step 830, the base station generates a channel estimate for the component carrier according to the SRS symbol.

DCI messages are typically decoded by the UE through a process called blind detection. Blind detection determines which set of control channel elements (CCE) in the Physical Downlink Control Channel (PDCCH) carries the DCI message for the UE without the need to send explicit control signaling. Reducing network overhead by allowing the UE to detect. In general, the UE performs blind detection in the search space of the physical downlink control channel (PDCCH) by trying to decode different sets of control channel elements (CCE) according to the known DCI format. Since SRS switching is a new technology, many UEs may not be aware of which DCI format is associated with a particular SRS configuration parameter/command. Embodiments of this disclosure use RRC messages to inform the UE of DCI message formats related to SRS parameters. This allows the UE to monitor the Physical Downlink Control Channel (PDCCH) for DCI format and modify these SRS transmission/switching operations accordingly.

FIG. 9 shows an example communication sequence 900 for using an RRC message to inform a UE of a DCI format used to signal SRS configuration parameters on a PDCCH. As shown, the base station 220 sends an RRC message 921 to the UE 210. RRC message 921 sets that the DCI message format is associated with a particular SRS signaling command. For example, RRC message 921 may specify a particular DCI message format to indicate the SRS transmit power level. As another example, RRC message 921 may specify a particular DCI message format for triggering SRS symbol transmission on the same component carrier used to transmit the DCI message. As yet another example, RRC message 921 may also specify a particular DCI message format to trigger inter-carrier transmission of SRS symbols on a component carrier different from that used to transmit the DCI message. Good. As yet another example, RRC message 921 triggers SRS symbol transmissions and associated SRS transmit power levels for the same or different CCs, for one or more CCs, and for one or more UEs. May specify a specific DCI message format for. After that, the base station 220 transmits a DCI message 922 having a DCI format indicated by the RRC message 921 to the UE 210. The UE 210 detects the DCI message 922 by monitoring the PDCCH for the DCI message format indicated by the RRC message 921 and sends the SRS symbol 972 on the component carrier 942 according to the SRS configuration parameters associated with the DCI message 922. To do. The DCI message 922 may be sent on the component carrier 942 or a different component carrier.

FIG. 10 is a flowchart of an example method 1000 for performing an aperiodic SRS transmission based on a DCI message format communicated on a PDCCH, which may be performed by a UE. In step 1010, the UE receives a radio resource control (RRC) message that specifies a downlink control information (DCI) message format for signaling SRS parameters. In step 1020, the UE monitors the physical downlink control channel (PDCCH) for the DCI message format specified by the RRC message. In step 1030, the UE detects a DCI message having a DCI message format in the PDCCH. In step 1040, the UE transmits SRS symbols on the component carrier according to SRS configuration parameters related to DCI message format.

FIG. 11 is a flowchart of an example method 1100 for performing channel estimation according to SRS transmissions, which may be performed by a base station. In step 1110, the base station sends a radio resource control (RRC) message specifying a downlink control information (DCI) message format for signaling SRS parameters. In step 1120, the base station transmits a DCI message having a DCI format on a physical downlink control channel (PDCCH). In step 1130, the base station receives the SRS symbol on the component carrier according to the SRS setting parameter. In step 1140, the base station generates a channel estimate for the component carrier according to the SRS symbol.

Different UEs may have different uplink carrier aggregation capabilities. For example, some UEs may be able to transmit uplink signals and/or receive downlink signals simultaneously on different numbers of component carriers. Further, the UE may have different uplink RF frequency alignment delays. The RF frequency matching delay may also be referred to as RF frequency matching time, RF frequency matching gap, or SRS switching gap, SRS switching time, etc. for SRS switching. Embodiments of this disclosure allow a base station to adjust uplink carrier switching settings for a given UE based on the UE's uplink carrier aggregation capabilities.

FIG. 12 shows an example communication sequence 1200 for assigning uplink carrier switching settings for a given UE based on the UE's uplink carrier aggregation capability. As illustrated, the UE 210 reports the uplink carrier aggregation capability 1221 to the base station 220. The uplink carrier aggregation capability 1221 may specify the number of component carriers with which the UE 210 can simultaneously transmit the uplink signal and/or the uplink RF frequency adjustment delay of the UE 210. Next, the base station 220 may allocate the uplink carrier switching setting 1222 to the UE based on the uplink carrier aggregation capability 1221 and send the uplink carrier switching setting 1222. The uplink carrier switch configuration 1222 can be configured in various ways, such as via a higher layer signaling channel (eg, in an RRC message), a media access control (MAC) signaling channel, or a PDCCH (eg, in a DCI message). It may be communicated. Upon reception, the UE may transmit SRS symbols 1261, 1262, 1263 on the component carriers 1241, 1242, 1245 according to the uplink carrier switching setting 1222.

FIG. 13 is a flowchart of an example method 1300 for assigning an uplink carrier switching setting to a UE, which may be performed by a base station, based on the UE's uplink carrier aggregation capability. In step 1310, the base station receives an uplink control signal indicating the uplink carrier aggregation capability of the UE. In step 1320, the base station assigns an uplink carrier switching setting to the UE based on the UE's carrier aggregation capability. In step 1330, the base station sends a downlink control signal instructing the UE to transmit SRS symbols on the aggregated set of component carriers based on the uplink carrier switching setting.

FIG. 14 is a flowchart of an example method 1400 for performing SRS transmission on a component carrier, which may be performed by a UE. In step 1410, the UE transmits an uplink control signal indicating the uplink carrier aggregation capability of the UE. In step 1420, the UE receives the uplink carrier switching setting from the base station. In step 1430, the UE transmits the SRS symbol on the component carrier according to the uplink carrier switching setting.

In some embodiments, a UE may be assigned different aggregated component carrier sets associated with different base stations. FIG. 15 is a diagram of a network 1500 in which a UE 210 is assigned an aggregated set of component carriers 1540 associated with a base station 220 and an aggregated set of component carriers 1550 associated with a base station 230. Each of the component carriers in the aggregated set of component carriers 1540 and the aggregated set of component carriers 1550 are represented by different sub-labels, as indicated by the labels (f1, f2,...f5, f6, f7...f9). Has a carrier frequency. The labels (f1, f2, ...f5, f6, f7, ...f9) imply a relationship/order between the subcarrier frequencies of the corresponding component carriers 1541-1545, 1556-1557, or otherwise. It should be recognized that it is not shown. By way of example, component carrier 1541 may have a higher subcarrier frequency than component carrier 1542 in some embodiments and may have a lower subcarrier frequency than component carrier 1542 in other embodiments. Similarly, the component carriers in a given set of aggregated component carriers are not necessarily adjacent in the frequency domain or otherwise contiguous with each other. By way of example, one or more subcarrier frequencies of the individual component carriers 1541, 1542, 1545 within the aggregated set of component carriers 1540 may be compared to individual component carriers 1551, 1552 within the aggregated set of component carriers 1550, It may be interleaved with one or more subcarrier frequencies of 1555.

UE 210 receives downlink signals from base station 220 on one or more of component carriers 1541-1545 in aggregated component carrier set 1540 in accordance with carrier aggregation and/or carrier selection transmission schemes, and The uplink signal may be transmitted to the base station 220. Similarly, the UE 210 receives downlink signals from the base station 230 on one or more of the component carriers 1551-1555 in the aggregated set of component carriers 1550 according to a carrier aggregation and/or carrier selection transmission scheme. And/or uplink signals may be transmitted to the base station 230. The BSs 220, 230 may be connected via a high speed backhaul, which is used to communicate data and/or control signaling for carrier aggregation and/or coordinated multipoint (CoMP) transmissions. Good. Alternatively, the BSs 220 and 230 may be connected with a non-ideal backhaul and the scenario corresponds to a dual connectivity scenario and may have multiple TAGs. Both are considered in this disclosure.

The base stations 220, 230 select (each) the component carrier to be used for uplink/downlink data transmission and to select the transmission parameters for uplink/downlink data transmission. Channel estimation may need to be performed on component carriers 1541-1545 and component carriers 1551-1555 periodically or aperiodically. Accordingly, UE 210 transmits SRS symbols 1521, 1522, 1525 on (respectively) component carriers 1541, 1542, 1545 and SRS symbols 1566, 1567, 1569 on (respectively) component carriers 1556, 1557, 1559. You may need. In some embodiments, the UE 210 may not be able to simultaneously transmit uplink signaling on all component carriers within the aggregated component carrier set 1540 and/or the aggregated component carrier set 1550, As a result, it may be necessary to perform SRS switching.

In particular, the propagation delay between UE 210 and base station 220 may be different than the propagation delay between UE 210 and base station 230. Thus, uplink transmission on component carriers 1541, 1542, 1545 may require different timing advance (TA) adjustments than uplink transmission on component carriers 1541, 1542, 1545. Generally, the initial uplink TA adjustment value is determined by a random access procedure. In particular, the UE 210 generally sends a random access preamble to the base stations 220, 230, which then estimate their respective TA values based on the propagation delay associated with the random access preamble and specify the TA value. The corresponding corresponding random access response (RAR) is sent to the UE 210. The UE 210 then uses the initial TA value to send the SRS symbols and other data on the PUCCH and/or PUSCH, and the base stations 220, 230 are based on the propagation delay measured according to the SRS symbols, Update the value constantly.

Since exchanging random access preambles and/or RAR messages prior to SRS symbol transmission may delay SRS symbol transmission excessively, it must be performed in the SRS switching procedure. May introduce significant latency. To reduce the latency associated with random access procedures during SRS switching, the base station 220 sends a dual connectivity constraint 1522 to the UE 210. The dual connectivity constraint 1522 prohibits the UE 210 from switching from a source component carrier in the aggregated component carrier set 1540 to a target component carrier in the aggregated component carrier set 1550 during the set period, The reverse is also done. Although the dual connectivity constraint 1522 is shown as being transmitted by the base station 220, it will be appreciated that the dual connectivity constraint may be transmitted by any network side device, such as the base station 230 or another network controller. Should be.

In one example, UE 210 accomplishes this by using different transmit chains (TX chains) to transmit uplink signaling on respective sets 1540, 1550 of aggregated component carriers. As an example, UE 210 does not use TX chain 218 to transmit any of SRS symbols 1566, 1567, 1569 on component carriers 1556, 1557, 1559, and on (respectively) component carriers 1541, 1542, 1545. The first TX chain 219 may be used to transmit the SRS symbols 1561, 1562, 1565. Similarly, UE 210 does not use TX chain 219 to transmit any SRS symbols on component carriers 1541, 1542, 1545 in the aggregated set of component carriers 1540, and (respectively) component carriers 1555, 1556. , 1559 may be used to transmit SRS symbols 1565, 1566, 1569 on TX chain 219.

FIG. 16 is a flowchart of an example method 1600 for transmitting SRS symbols on different aggregated component carrier sets based on dual connectivity constraints, which may be performed by a UE. In step 1610, the UE receives a downlink control signal designating a dual connectivity cell group configuration constraint from the network controller. In step 1620, the UE transmits the SRS symbol on the component carrier monitored by the first base station without switching the first transmission chain (TX chain) to the target component carrier monitored by the second base station. To use the first TX chain. In step 1630, the UE does not switch the second TX chain to the target component carrier monitored by the first base station, and transmits the SRS symbol on the component carrier monitored by the second base station to transmit the SRS symbol. Use 2 TX chains.

The dual connectivity constraint may be primarily used when there is no high speed backhaul between base stations 220 and 230 and may not apply in scenarios where there is a high speed backhaul connection between base stations 220 and 230. ..

When the TX and/or RX chain is adjusted and switched from the source component carrier to the target component carrier, generally related to adjusting the hardware component of the TX or RX chain from the source subcarrier frequency to the target subcarrier frequency There is an RF frequency matching delay.

In the case where both the TX and RX chains are switched from the source component carrier to the target component carrier, the UE's downlink RF frequency alignment delay may be approximately equal to the UE's uplink RF frequency alignment delay. FIG. 17 shows an example of the transmission occurring before and immediately after the UE 210 switches from the source component carrier to the target component carrier in the period t3. In this example, the UE 210 RX chain 214 is used to receive both the downlink signal 1714 on the source component carrier and the downlink signal 1724 on the target component carrier, and the UE 210 TX chain 218 is , Used to transmit both the uplink signal 1712 on the source component carrier and the uplink signal 1722 on the target component carrier. Therefore, when the UE 210 switches to the target component carrier at the beginning of the period t4, both the TX chain 218 and the RX chain 214 need to be tuned to the center frequency of the target component carrier, which results in the downlink RF frequency. Both the alignment delay and the uplink RF frequency alignment delay have durations approximately equal to the period t4. Therefore, the base station associated with the target component carrier should not start sending downlink transmission 1724 until period t5 and should not expect to start receiving uplink transmission 1722 until period t5. Other examples may exist, such as when the component carriers are Time Division Duplex (TDD), so that the uplink and downlink transmissions do not overlap in the time domain. In such an example, SRS switching may be performed on the uplink TX chain and the downlink RX chain may monitor both the source and target component carriers simultaneously without switching.

In the case where only the TX chain of the UE is switched from the source component carrier to the target component carrier, as can happen in the case where the UE contains well separated RX chains assigned to the source and target component carriers, the downlink of the UE The RF frequency alignment delay may be near zero, or may be much smaller than the UE's uplink RF frequency alignment delay.

FIG. 18 shows an example of transmissions that occur before and immediately after the UE 210 is switched from the source component carrier to the target component carrier. In this example, the UE 210 RX chain 216 is used to receive the downlink signal 1814 on the source component carrier and the UE RX chain 217 is used to receive the downlink signal 1824 on the target component carrier. And the TX chain 218 of the UE 210 is used to transmit both the uplink signal 1812 on the source component carrier and the uplink signal 1822 on the target component carrier via carrier switching. Therefore, when the UE 210 switches to the target component carrier at the beginning of the period t4, only the TX chain 218 needs to be adjusted to the center frequency of the target component carrier. As a result, the UE 210 experiences minimal downlink RF frequency alignment delay, and the base station associated with the target component carrier may initiate downlink transmission 1824 during period t4, but uplink transmission until period t5. This means that you should not expect to start receiving 1822. Other examples may exist, such as when the component carriers are Time Division Duplex (TDD), so that the uplink and downlink transmissions do not overlap in the time domain. In such an example, SRS switching may be performed on the uplink TX chain and the downlink RX chain may monitor both the source and target component carriers simultaneously without switching.

Since the duration of the uplink/downlink RF frequency alignment delay of the UE affects the timing of uplink and downlink transmission on the target component carrier, the UE shall notify the base station of these RF frequency alignment delays. May be useful, or even necessary. Embodiments of this disclosure provide a low-overhead frame format for signaling UE uplink/downlink RF frequency alignment delay. FIG. 19 is a diagram of a frame format of an uplink control message 1901 for signaling the uplink and downlink RF frequency alignment delay of the UE. The uplink control message 1901 includes an uplink RF frequency adjustment delay field 910 and a flag field 920. The uplink RF frequency alignment delay field 910 may be composed of two or more bits indicating the duration of the uplink RF frequency alignment delay of the UE. The bits may represent the duration of the uplink RF frequency alignment delay of the UE as a fraction of the OFDM symbol duration, for example, 0 symbol duration, 0.5 symbol duration, 1 symbol duration, 1.5 symbol duration, etc. .. The flag field 920 is set to a first value indicating that the UE's downlink RF frequency alignment delay is equal to the uplink RF frequency alignment delay indicated by field 910, or the UE's downlink RF frequency alignment delay. May be comprised of a single bit set to a second value indicating that is equal to 0 (otherwise below a lower threshold).

FIG. 20 is a flowchart of an example method 2000 for signaling UE uplink and downlink RF frequency alignment delays that may be performed by a UE. In step 2010, the UE sets the uplink RF frequency alignment delay field of the uplink control message to indicate the duration of the uplink RF frequency alignment delay of the UE. In step 2020, the UE sets the flag field of the uplink control message according to the downlink RF frequency alignment delay. In particular, the UE sets the flag field to a first value when the UE's downlink RF frequency alignment delay is equal to the uplink RF frequency alignment delay, or the UE's downlink RF frequency alignment delay is zero. (Otherwise below the lower threshold) when set to the second value. The flag field may in some cases be referred to as the downlink RF frequency match field.

FIG. 21 is a flowchart of an example method 2100 for determining an uplink and downlink RF frequency alignment delay for a UE that may be performed by a base station. In step 2110, the base station receives an uplink control message from the UE. In step 2120, the base station determines the uplink RF frequency alignment delay of the UE according to the uplink RF frequency alignment delay field of the uplink control message. In step 2130, the base station determines the downlink RF frequency alignment delay of the UE according to the flag field of the uplink control message.

As mentioned above, the UE may be instructed to periodically transmit SRS symbols on the component carriers in the aggregated set of component carriers according to a periodic SRS switching schedule. In some cases, one of the component carriers in the aggregated set of component carriers may be deactivated before the duration of the periodic SRS switching schedule expires. In such cases, the UE may need to adapt the periodic SRS switching schedule to compensate for deactivated carriers. In the example of this disclosure, the UE is preconfigured to adapt the periodic SRS switching schedule when the component carrier is deactivated.

FIG. 22 shows an example communication sequence 2200 for adapting a periodic SRS switching schedule in response to component carrier deactivation. In this example, UE 210 is instructed to periodically transmit SRS symbols on component carriers 2241, 2242, 2243 in aggregated component carrier set 1240. Therefore, UE 210 periodically transmits SRS symbols 2261-2268 on component carriers 2241, 2242, 2243 during the first set of periods. At some point before the duration of the SRS switch schedule expires, the UE 210 receives a deactivate component carrier message 1222 indicating that the component carrier 2242 is deactivated. The UE 210 is pre-configured to adapt the SRS switching schedule to compensate for the deactivation of the component carrier 2242, so that the UE 210 may not be on the deactivated component carrier 2242 during the second set of periods. Therefore, no SRS symbol is transmitted, and SRS symbols 2271-2283 are transmitted on the component carriers 2241 and 2243 during the setting of the second period.

FIG. 23 is a flowchart of an example method 2300 for adjusting a periodic SRS transmission schedule in response to activation of component carriers, which may be performed by a UE. In step 2310, the UE transmits at least one SRS symbol on each component carrier in the aggregated set of component carriers according to the SRS switching setting during the first set of periods. In step 2320, the UE receives a control message indicating deactivation of at least one component carrier in the aggregated set of component carriers. The control message may also be a medium access control (MAC) message or other type of control message (eg, DCI message, RRC message, etc.) or implicit via the expiration of an activation timer that is not reset due to new activity. Good. In step 2330, the UE adjusts the periodic SRS switching schedule to supplement the deactivated component carrier. The adjustment may include reassigning the periodic SRS symbol transmission from the deactivated component carrier to one of the remaining active component carriers. Alternatively, the adjustment may include removing deactivated component carriers from a periodic schedule (eg, a round robin type schedule, etc.), which causes the SRS symbols to more frequently remain in the remaining active components. Sent on the carrier. In step 2340, the UE does not transmit any SRS symbols on the at least one deactivated component carrier during the second set of periods, and the adjusted periodic SRS during the second set of periods. Send at least one SRS symbol on each remaining component carrier in the aggregated set of component carriers according to the switching schedule.

In some scenarios, the base station may desire to broadcast a control message that includes multiple SRS parameters (including SRS power control and/or SRS triggers) for one or more UEs. Embodiments of this disclosure include, within a control message or separately via higher layer signaling, a plurality of SRS commands embedded in the control message among individual corresponding UEs of their corresponding SRS commands. Communicate flag bits to notify location. 24A-24D show frame formats for control messages 2410, 2420, 2430, 2440 that carry multiple SRS commands 2456-2459. Each of the SRS commands 2456-2459 may be targeted to different UEs and may have different lengths depending on the information conveyed by the SRS command (eg, SRS parameters, etc.).

As shown in FIG. 24A, the control message 2410 includes flag bits 241-21419 and SRS instructions 2456-2459. Flag bits 241-21419 can be used to locate SRS instructions 2456-2459 in control message 2140. Flag bit 2411 indicates the starting bit position (B1) for SRS instruction 2456. Flag bit 2416 indicates the length (L1) of SRS instruction 2456. Therefore, flag bits 2411, 2116 can be used to identify the location of SRS command 2456 by the corresponding UE. Similarly, flag bit 2412 indicates the start bit position (B2) for SRS instruction 2457, flag bit 2417 indicates the length (L2) of SRS instruction 2457, and flag bit 2414 indicates the start bit for SRS instruction 2459. The position (BN) is indicated and the flag bit 2419 indicates the length (LN) of the SRS instruction 2456.

Similarly, as shown in FIG. 24B, control message 2420 includes flag bits 2421-2424 that can be used to find SRS instruction 2456-2459 in control message 2410. Flag bit 2421 indicates the length (L1) of SRS instruction 2456, flag bit 2422 indicates the length (L2) of SRS instruction 2457, and flag bit 2424 indicates the length (LN) of SRS instruction 2459. The starting bit position (B1) of the SRS command 2456 may be prior information of the UE receiving the control message 2420. Alternatively, the start bit position (B1) of SRS instruction 2456 may be signaled by another flag bit not shown in Figure 24B. Based on knowledge of the starting bit position (B1) of SRS instruction 2456, the intended recipient of SRS instruction 2456 can use flag bit 2421 to find SRS instruction 2456. Similarly, the intended recipient of SRS instruction 2457 determines the starting bit position (B2) of SRS instruction 2457 by adding the number of bits indicated by flag bit 2421 to the starting bit position (B1) of SRS instruction 2456. Then, flag bit 2422 can be used to find SRS instruction 2457. Similarly, the intended recipient of SRS instruction 2459 adds the sum of the number of bits represented by all flag bits preceding flag bit 2424 to the start bit position (B1) and adds the start bit position (BN ), and then flag bit 2424 can be used to locate SRS instruction 2457.

In the control message 2430 illustrated by FIG. 24C, flag bits 2431-2434 are interleaved with their corresponding SRS instructions 2456-2459. Similar to control message 2420, flag bit 2431 indicates the length of SRS instruction 2456 (L1), flag bit 2432 indicates the length of SRS instruction 2457 (L2), and flag bit 2434 indicates the length of SRS instruction 2459 (L2). LN) is shown. The intended recipient of SRS instruction 2456 can use flag bit 2431 to locate SRS instruction 2456. The intended recipient of SRS instruction 2457 can use flag bit 2431 to find flag bit 2432 and flag bit 2432 to find SRS instruction 2457. The intended recipient of SRS instruction 2459 can find flag bit 2439 based on all of the flag bits that precede flag bit 2439, and then use flag bit 2439 to find SRS instruction 2459. As yet another alternative, one or more of the aforementioned flag bits may be transmitted via higher layer signaling and then used to find SRS instruction 2456-2459 in control message 2440 illustrated by FIG. 24D. May be.

FIG. 25 is a flowchart of an example method 2500 for finding SRS parameters in a control message, which may be performed by a UE. In step 2510, the UE receives a single downlink control message including multiple SRS parameters and one flag field. In step 2520, the UE identifies the position of the SRS command among the multiple SRS commands in a single downlink control message based on the flag field. In step 2530, the UE transmits SRS symbols on the component carrier based on the SRS command.

FIG. 26 is a flowchart of an example method 2600 for sending a control message that includes SRS commands for different UEs, which may be performed by a base station. In step 2610, the base station generates a single downlink control message including multiple SRS commands. In step 2620, the base station generates one flag field for each SRS command based on the position and/or length of the SRS command. In step 2630, the base station sends a single downlink control message and flag field to the UE. In step 2640, the base station receives SRS symbols from the UE according to the SRS command embedded in the single downlink control message. In step 2650, the base station generates a channel estimate according to the SRS symbol.

In some embodiments, the UE may also puncture the portion of the uplink signal transmitted on the target component carrier that overlaps the uplink RF frequency alignment delay after switching from the source component carrier to the target component carrier. Good. FIG. 27 shows an uplink transmission 2730 that occurs before and immediately after the UE 210 switches from the source component carrier to the target component carrier. In this example, the TX chain 218 of UE 210 is used to transmit both the uplink signal 2720 on the source component carrier and the uplink signal 2730 on the target component carrier. As a result, the UE 210 has an uplink RF frequency alignment delay with a duration equal to the period t4. In this example, uplink transmission 2730 is scheduled from time period t4 to t10. To compensate for the uplink RF frequency alignment delay, the UE 210 punctures the portion 2731 of the uplink transmission 2730 that overlaps the time period t4. In one example, the UE 210 may also perform rate adjustments (eg, rate matching) on the non-punctured portion of the uplink 2730 to compensate for the bandwidth lost from puncturing the portion 2731. Good. Puncturing may occur on the source component carrier and/or the target component carrier. Similarly, puncturing or rate matching in DL may occur.

FIG. 28 is a flowchart of an example method 2800 for supplementing an uplink RF frequency alignment delay after switching from a source component carrier to a target component carrier, which may be performed by a UE. In step 2810, the UE transmits a first uplink signal that carries at least a first SRS symbol on the first component carrier. In step 2820, the UE switches from the source component carrier to the target component carrier according to the SRS switching schedule. In step 2830, the UE punctures the portion of the second uplink signal that corresponds to the duration of the uplink RF frequency alignment delay. In step 2840, the UE transmits a second uplink signal on the target component carrier.

Embodiments of this disclosure provide techniques for handling scheduling collisions between SRS symbols and other uplink signals. In particular, some types of uplink signals may be scheduled on the primary component carrier at the same time that the UE is scheduled to transmit SRS symbols on the secondary component carrier. If the uplink signal scheduled on the primary component carrier meets the criteria, the UE prioritizes transmission of the uplink signal on the primary component carrier and delays the scheduled transmission of SRS symbols on the secondary component carrier. You may let it or else cancel it.

FIG. 29 shows transmissions that occur before and immediately after the UE 210 switches from the primary component carrier to the secondary component carrier. In this example, the TX chain 214 of the UE 210 performs both reception of the downlink signal 2912 and transmission of the uplink acknowledgment (acknowledgement, ACK) and/or NACK message 2914 on the primary component carrier, and the secondary Used to transmit SRS symbol 2924 on the component carrier. The ACK message 2914 indicates to the base station associated with the primary component carrier that the downlink transmission 2912 was successfully decoded by the UE. The ACK message 2914 is scheduled to be transmitted on the primary component carrier during the same period t7 when the SRS symbol 2924 was originally scheduled to be transmitted on the secondary component carrier. In this example, the ACK message 2914 is preceded and the SRS symbol is delayed until period t9. Period t9 may be the next available opportunity to transmit SRS symbol 2924 on the secondary component carrier. In another example, the SRS symbols may be delayed indefinitely.

In FIG. 29, the ACK message 2914 has priority over the SRS symbol 2924, but other uplink symbols (for example, channel state information (CSI) message etc.) may also have priority over SRS symbol transmission. Should be recognized.

FIG. 30 is a flowchart of an example method 2800 for collision handling during SRS switching that may be performed by a UE. In step 3010, the UE determines that the uplink signal is scheduled on the primary component carrier during the same period that the SRS symbol is scheduled to be transmitted on the primary component carrier. In step 3020, the UE does not transmit SRS symbols on the secondary component carrier during the period, but transmits uplink control signals on the primary component carrier during the period.

In some embodiments, a group of component carriers monitored by the same may be associated with a common timing advance group (TAG). One or more component carriers in the timing advance group may not support PUCCH/PUSCH signaling. In FIG. 31, the UE 210 allocates the component carriers 3141, 3142, 3145 related to the first TAG (TAG#1) and the component carriers 3156, 3157, 3159 allocated to the second TAG (TAG#2). FIG. 3 is a diagram of a network 3000 created. UE 210 may use the same TA adjustment value when transmitting uplink signals (eg, SRS symbols, etc.) on component carriers 3141, 3142, 3145 associated with TAG#1. Similarly, UE 210 may use the same TA adjustment value when transmitting uplink signals (eg, SRS symbols, etc.) on component carriers 3156, 3157, 3159 assigned to TAG#2. In this example, component carrier 3142 and component carrier 3157 do not support PUCCH/PUSCH signaling.

FIG. 32 is a diagram of a network 3200 in which a UE 210 transmits SRS symbols on component carriers 3241-3243 in a group of aggregated component carriers 3240 and component carriers 3254-3256 in a group of aggregated component carriers 3250. .. Component carriers 3241-3243 in group 3240 of aggregated component carriers support PUCCH/PUSCH signaling, while component carriers 3254-3256 in group 3250 of aggregated component carriers are PUCCH/PUSCH signaling (signaling). May not be supported and only SRS and possibly RACH may be supported. UE 210 receives downlink signaling from the network on component carriers 3241-3243 in group 3240 of aggregated component carriers and component carriers 3254-3256 in group 3250 of aggregated component carriers, and component carrier 3267-3269. To do. In cases where carrier aggregation is applied, downlink signaling may be received on more than one of the component carriers 3241-3243, 3254-3256, 3267-3269.

In some embodiments, uplink RF frequency alignment delay may be experienced during SRS switching. FIG. 33 is a diagram of an uplink transmission that occurs during an SRS switching operation. In this example, the TX chain 218 of UE 210 is used to transmit the uplink signal 3220 on the source component carrier and the SRS symbol 3332 on the target component carrier. UE 210 experiences an uplink RF frequency alignment delay with a duration equal to period t9. Uplink signal 3320 carries SRS symbols 3322. The transmission characteristics of the SRS symbol 3322, such as the transmission power level, may be based on the characteristics of PUSCH/PUCCH signaling in the uplink signal 3320. The transmission characteristics of SRS symbol 3332 may be independent of PUSCH/PUCCH signaling.

In some embodiments, SRS switching is performed on Time Division Duplex (TDD) channels. FIG. 34 is a diagram of transmissions that occur within subframe 3400 during an SRS switch operation. Switch from the source component carrier to the target component carrier. In this example, the transceiver (TX/RX) chain 212 of the UE 210 is both receiving downlink transmission 3412 on the source component carrier and transmitting SRS symbol 3424 and uplink signal 3422 on the target component carrier. Used to do. UE 210 has an RF frequency alignment delay with a duration less than the guard interval between the uplink portion 3420 of subframe 3400 and the downlink portion 3410 of subframe 3400. As a result, switching the TX/RX chain 212 from the source component carrier to the target component carrier does not interfere with the downlink transmission 3412.

FIG. 35 is a diagram of transmissions that occur within subframe 3500 during an SRS switch operation. In this example, the TX/RX chain 212 of UE 210 is for both receiving downlink transmission 3512 on the source component carrier and transmitting SRS symbol 3524 and uplink signal 3522 on the target component carrier. used. The RF frequency alignment delay of the TX/RX chain 212 has a duration that exceeds the guard interval between the uplink portion 3520 of the subframe 3500 and the downlink portion 3510 of the subframe 3500, thus sourcing the TX/RX chain 212. Switching from a component carrier to a target component carrier interferes with or otherwise punctures or punctures the downlink transmission 3512, or drops one or more symbols of the downlink transmission 3512. Need.

FIG. 36 is a diagram of transmissions that occur within subframe 3600 during an SRS switch operation. In this example, UE 210's RX chain 216 is used to receive downlink transmission 3612 on the source component carrier, and TX chain 218 is SRS symbol 3622 on the target component carrier and on the source component carrier. Used to transmit both the uplink signal 3614. As such, TX chain 218 is switched from the source component carrier to the target component carrier before transmission of SRS symbol 3622, and then switched back to the source component carrier before transmission of uplink signal 3614. The RF frequency alignment delay of TX chain 218 has a duration that has a duration that exceeds the guard interval between the uplink portion 3520 and downlink portion 3510 of subframe 3500, while TX chain 218 does not Switched independently so that switching TX chain 218 to the target component carrier prior to transmission of SRS symbol 3622 does not interfere with the reception of downlink signal 3612. However, switching the TX chain 218 back to the source component carrier requires shortening or puncturing the uplink signal 3614 or dropping one or more symbols of the uplink signal 3614.

FIG. 37 is a diagram of transmissions that occur within subframe 3700 during an SRS switch operation. In this example, the TX chain 218 of UE 210 is used to transmit both the uplink signal 3614 on the source component carrier and the SRS symbol 3722 on the target component carrier. Therefore, the TX chain 218 is switched from the source component carrier to the target component in the middle of transmission of the uplink signal 3714 and the SRS symbol 3722. When the RF alignment delay of TX chain 218 has a non-zero duration, there is no guard interval between the uplink portion 3720 of subframe 3500 and the downlink portion 3710 of subframe 3700, so TX chain 218 is It may start its transition to the target component carrier prior to the start of the SRS symbol on the target CC. As a result, the uplink portion 3720 is shortened/punctured in the portion overlapping the UL RF frequency alignment time and SRS transmission.

Carrier aggregation (CA) and carrier selection are techniques that utilize multiple carriers to increase the available bandwidth available to a given mobile device. CA allows multiple carrier signals to be simultaneously communicated between a UE and a supporting base station. Typically, the UE may be configured with a set of carriers by a base station such as an enhanced NodeB (enhanced NodeB, eNB). In some cases, carriers may be from different frequency bands to add higher bandwidth to support high data rate communications and operations such as streaming video or large data files.

Another technique is to rely on carrier selection (CS) to allow the UE to support carriers larger than its capacity. Carrier switching/selection among all carriers available to the serving base station may allow the UE to access more carriers over time. In this approach, component carriers are selected based on several factors such as load balancing. The CS approach generally requires a much smaller UE extension than the CA approach, but one drawback for the CS is the transition time involved in carrier switching and selection.

During carrier selection, the mobile device may be assigned a set of component carriers. The base station and/or the mobile device monitor the channel quality of each carrier in the assigned set and when the criterion is met, eg, the channel quality of the target carrier exceeds that of the current component carrier by at least a threshold value. Then, the switching from the current carrier to the target carrier may be triggered. As used herein, the term "current carrier" refers to the original carrier that the mobile device is transitioning to during the switch operation, and the term "target carrier" refers to the destination to which the UE is switching during the switch operation. Indicates a carrier. The target carrier may support a higher bit rate than the current carrier, but nevertheless there are some latency and overhead costs that result from switching from the current carrier to the target carrier.

Overhead/latency costs can be particularly significant when beamforming transmissions are exchanged on the target carrier. In particular, mobile devices typically need to send a Sounding Reference Signal (SRS) on the carrier, which allows the base station to derive the complex channel response of the downlink channel and to select the appropriate downlink for the carrier. Beamforming parameters can be selected. The downlink channel response can be derived from the uplink SRS transmission in the TDD component carrier as the downlink and uplink channels on the same frequency are likely to have similar channel response due to the concept of channel reciprocity. However, the concept of channel reciprocity is typically not applicable to different carriers, as the channel response is typically frequency dependent. As a result, uplink SRS transmissions on one carrier are generally not useful in deriving the complex channel response of the other carrier. Therefore, the mobile device switching from the current carrier to the target carrier may need to perform SRS transmission on the target carrier before the beamforming transmission can be communicated by the base station. This can introduce latency in the cell switching process. Embodiments of this disclosure provide SRS frame configuration and SRS switching techniques that reduce the amount of latency associated with SRS transmissions when switching from a current carrier to a target carrier.

FIG. 38A shows a wireless network 3810 for supporting carrier aggregation and/or carrier switching. As shown, base station 3811 communicates with mobile device 3815 on different component carriers 3816, 3817. In some embodiments, component carrier 3816 is a primary component carrier (PCC) and component carrier 3817 is a secondary component carrier (SCC). In an embodiment, the PCC carries control information (eg, feedback from the mobile device 3815 to the base station 3811) and the SCC carries data traffic. In the 3GPP Rel-10 specifications, component carriers are called cells. When multiple cells are controlled by the same eNodeB, a single scheduler may perform cross scheduling of multiple cells. Regarding carrier aggregation, one high power node may operate and control several component carriers, thereby forming a primary cell (Pcell) and a secondary cell (Scell). The primary carrier communicated from the base station to the mobile device may be referred to as a downlink primary component carrier (Downlink Primary Component Carrier, DL PCC), while the primary carrier communicated from the mobile device to the base station is It may be referred to as an Uplink Primary Component Carrier (UL PCC). The secondary carrier communicated from the base station to the mobile device may be called a downlink secondary component carrier (Downlink Secondary Component Carrier, DL SCC), while the secondary carrier communicated from the mobile device to the base station is It may be called an Uplink Secondary Component Carrier (UL SCC). In the Rel-11 design, the eNodeB may control both macro cells and pico cells. In this case, the backhaul between the macrocell and the picocell is a fast backhaul. The eNodeB can dynamically control transmission/reception of both macro cells and pico cells.

In modern wireless networks, base stations may be grouped together to form a cluster of base stations. Each base station in the cluster may have multiple antennas and may provide wireless access to multiple mobile devices within the wireless coverage area of the corresponding base station. Resources may be assigned to mobile devices based on scheduling algorithms, eg, proportional fairness, round robin, etc. FIG. 38B illustrates a wireless heterogeneous network (HetNet) 3820 configured to support carrier aggregation and/or carrier selection. As shown, base stations 3821, 3822 communicate with mobile device 3825 on different component carriers 3826, 3827. Base station 3821 may be a high power node (eg, macrocell), and base station 3822 may be a low power node, eg, picocell, femtocell, microcell, repeater, remote radio head (RRH), remote radio unit. Alternatively, a distributed antenna or the like may be used. Therefore, the base station 3822 may have a smaller coverage area than the base station 3821. Low power nodes may provide improved cellular coverage, capacity and applications for homes and businesses, and metropolitan and rural public spaces.

FIG. 38C illustrates another wireless heterogeneous network (HetNet) 3830 configured to support carrier aggregation and/or carrier selection. As shown, base stations 3831, 3832, 3833 communicate with mobile device 3835 on different component carriers 3836, 3837, 3838. Base station 3831 may be a high power node (eg, macro cell) and base stations 3832, 3833 may be low power nodes, eg, pico cell, femto cell, micro cell, repeater, remote radio head (RRH), remote radio unit, distributed. It may be an antenna or the like.

38B-38C illustrate that base stations communicate with mobile devices on different component carriers, but in some implementations, base stations in Het-Net communicate with mobile devices on the same component carrier. It should be recognized that it may be.

Some Het-Nets may have multiple high power nodes and/or multiple low power nodes operating on multiple component carriers. Nodes within the same Het-Net may be interconnected by fast or slow backhaul connections depending on the placement. Fast backhaul connections may be utilized to improve coordination between nodes, such as to achieve joint transmit/receive. Multiple remote radio units may be connected by fiber cables to the same baseband unit of the eNodeB to support relatively low latency communication between the baseband unit and the remote radio units. In some embodiments, the same baseband unit handles coordinated transmission/reception of multiple cells. For example, the baseband unit may jointly transmit multiple cells to mobile device transmissions from multiple base stations to a terminal (eg, multipoint coordinated (CoMP) transmission) to achieve multipoint coordinated (CoMP) transmission. May be coordinated. As another example, the baseband unit may coordinate joint reception of signals communicated from a mobile device to multiple base stations to achieve multipoint coordinated (CoMP) reception. Fast backhaul connections may also be used to coordinate joint scheduling between different base stations. The densely located network is an extension of HetNet and includes a relatively large number of closely spaced low power nodes to provide improved coverage and throughput. Closely located networks may be particularly suitable for indoor and/or outdoor hotspot deployments.

In a wireless network, reference signals, data signals and control signals may be communicated on orthogonal time frequency resources. For example, each signal may be mapped to a different resource element (resource element, RE) in a resource block (resource block, RB) of the radio frame. FIG. 39 illustrates an example method 3900 for processing a signal during carrier selection that may be performed by a mobile device. In steps 3905 and 3910, the mobile device processes a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), respectively, to determine cell identity and frame timing of the physical broadcast channel. .. In step 3915, the mobile device processes a cell-specific reference signal (CRS) of the physical broadcast channel to obtain channel information. In step 3920, the mobile device obtains a system information broadcast (SIB) message for one or more carriers, eg, SIB1, SIB2, etc., to receive a physical broadcast channel (PBCH). To process. In step 3925, the mobile device processes the SIB message to obtain downlink control information (DCI) associated with the corresponding component carrier. The DCI may indicate transmission parameters (eg, modulation and coding scheme (MCS) parameters, etc.) used to transmit each candidate carrier. In step 3930, the mobile device processes the CRS in the candidate carriers to estimate the channel quality associated with each of the respective candidate carriers.

In step 3935, the mobile device performs cell selection based on the channel quality information derived in step 3930. In steps 3940 and 3945, the mobile device begins monitoring the selected carrier and performs a random access transmission (RACH) uplink transmission to request the resources of the selected carrier to be scheduled by the mobile device. To do. In step 3950, the mobile device transitions from RRC_IDLE mode to RRC_CONNECTED mode. This may be achieved by exchanging messages with the base stations associated with each carrier.

In some networks, it may be desirable to implement beamforming and cell selection techniques within the same communication session. Before a beamforming transmission can be performed on a Time Domain Duplex (TDD) component carrier, the mobile device typically needs to transmit a Sounding Reference Signal (SRS) on the carrier, which causes the base station to downlink. We can derive the complex channel response of the link channel and select appropriate downlink beamforming parameters. The downlink channel response can be derived from the uplink SRS transmission in the TDD component carrier as the downlink and uplink channels on the same frequency are likely to have similar channel response due to the concept of channel reciprocity.

However, channel reciprocity is typically frequency dependent, so uplink SRS transmissions on one carrier are generally not useful in deriving the complex channel response of the other carrier. Therefore, a mobile device that switches from one carrier to another may need to perform SRS transmission on the new carrier before the beamforming transmission can be communicated by the base station. This can introduce latency in the cell switching process.

One solution for reducing latency during cell switching is for the mobile device to perform SRS transmissions on all candidate carriers, including candidate carriers that are not used by the mobile device. However, in the current LTE system, when there is an imbalance between downlink and uplink control channels, e.g., there are more downlink control channels than uplink control channels, the mobile device may be uplinked on the component carrier. You may not be allowed to send Link SRS. In particular, when there is a higher demand for downlink traffic, e.g. when more downlink traffic is being communicated on a given carrier than the uplink traffic, the network operator is Many resources may be allocated to carry downlink traffic and control signaling.

Moreover, some mobile devices may be able to transmit SRS signaling simultaneously on a limited number of uplink component carriers (eg, two component carriers). Table 1 provides the proposed carrier aggregation settings for the 4th generation radio access network (RAN4) standard.

The imbalance in the number of DL-UL CCs can be even more significant with Rel-13 eCA standardized up to 32 DL CCs per UE. Thus, there may be situations where most of the UE's DL CCs cannot benefit from channel reciprocity.

What is needed is an embodiment that allows a mobile device to quickly switch from one TDD component carrier to another while still utilizing beamforming.

In a CA, a UE may be able to send PUSCH, SRS, RACH and DMRS on one UL CC, two UL CCs or more UL CCs (not currently available). One of the UL CCs is configured as a PCell for the UE from which the UE sends PUCCH and the other UL CC, if present, may or may not support PUCCH Set as SCell. UL PCell and UL SCell may be in the same band or different bands, they may be FDD, TDD or FDD+TDD, and they may be in the same Timing Advance Group (TAG) or different TAGs. The UE may be configured with more SCells having only DL, which may be in the same band or several bands operating in FDD, TDD or FDD+TDD. All of these scenarios may be considered for switching based on SRS carriers, unless they have only FDD CCs. The following table shows some examples.

It should be noted that the current RAN4 requirements (bandwidth combinations, etc.) do not support some CA configuration scenarios, but the RAN1 design need not be limited to the currently supported scenarios. Nevertheless, when operating in SRS carrier-based switching, the network needs to ensure that its operation complies with RAN4 requirements.

To enable fast carrier switching between TDD CCs, the mobile device may need to perform SRS transmissions on each candidate component carrier. The mobile device may be instructed by the base station or controller to switch from one component carrier to another. For example, the mobile device may be instructed to suspend its transmission on the first component carrier, switch to the second component carrier, and then transmit the SRS on the second component carrier. .. The instructions may specify the resources to perform the SRS transmission by indicating the antenna port. The instructions may also identify timing advance and transmit power levels for SRS transmissions. Then, the UE may switch back to the first component carrier. Alternatively, the switching may be triggered by dynamic signaling. The network may need to first configure the UE with SRS on all TDD CCs, even if the UE's UL CA capability is fairly small. Some explanations are provided below.

Some general behavioral designs are discussed. For ease of discussion, these are categorized into three levels:
Carrier level setting for SRS and carrier level for switching from one carrier to another,
Subframe level regarding on which subframe SRS switching and transmission should be performed and the relationship with other transmissions on that subframe, and
Symbol level for SRS switching symbols and transmission symbols. FIG. 4 shows a switching method based on the SRS carrier of the embodiment. As shown, the SRS switching is performed at the carrier level, subframe level and symbol level, and D/S/U represents downlink/special/uplink subframe, respectively.

There are several considerations regarding general operating principles, requirements and designs at the carrier level. To enable fast carrier switching to and between TDD Component Carriers (CCs), the network may first have more TDD CCs or potential In general, it is necessary to configure the UE with SRS on all TDD CCs. The UE can then switch to and between these carriers and send the SRS. The switching may be in accordance with a network setting or a network instruction including information about the switching source carrier and the switching destination carrier. The SRS transmission on the CC that is the switching destination also follows the network settings or instructions including the transmission power, timing, bandwidth, etc.

During the switch from CC1 to CC2, the UE shall stop any possible transmission on CC1 according to the indicated timing, switch to CC2 within a temporary period and signal according to the corresponding network indication. To do. After transmission, the UE may switch back to CC1 or switch to CC3 according to the corresponding network indication. This operation may be considered as another switching operation.

Thus, a typical switching operation involves one or more of the following elements: 1) Switching source CC (switching-from CC), the source CC the UE is switching from. 2) Timing of switching source, time of leaving CC of switching source (SC-FDMA symbol position). 3) Switching destination CC (switching-to CC), destination UE switching destination CC. 4) Transmission on the CC of the switching destination including the signal format, content, resources, timing, power, etc. of the transmission on the CC of the switching destination. 4) Next switching information such as whether the UE should switch back to the switching source CC, proceed to another CC, stay in the current CC, etc.

In case the UE does not support UL CA on all TDD CCs to allow the UE to send SRS on more TDD CCs or potentially even all TDD CCs over time. Also needs to allow SRS to be configured on these TDD CCs. This is not allowed by current standards. Therefore, the main standard impact is to allow the number of TDD carriers configured for SRS transmission to exceed the number of carriers indicated by the UL CA capability of the UE.

SRS transmission needs to be configured on all TDD CCs. In other words, each TDD CC needs to be explicitly or implicitly set by SRC bandwidth setting, subframe setting, comb of transmission, antenna port, cyclic shift, etc. by RRC signaling. For different transmission modes, the SRS densities in time may be different, so that the precoding-based transmission modes should have a higher density of SRSs. In addition, SRS power control parameters for each TDD CC need to be set.

Current power control for SRS assumes the presence of PUSCH on the same CC, so some changes are needed for SRS power control. Like SRS power control parameters similar to PUSCH power control mechanism, SRS power control settings that do not rely on PUSCH on the same CC need to be specified.

The CC set may be used to simplify the SRS transmission setup. A set of co-located CCs in the same band sharing the same set of antennas corresponding to the same TAG can be configured as one CC set, which includes power control parameters, timing advance (TA), path loss estimation, They may share common properties such as quasi-co-location (QCL) properties. The method disclosed in 91035003US01 can be adopted here especially for the purpose of SRS setting. In general, TDD CC and FDD CC are in different sets.

To support switching based on SRS carriers, the switching source carrier and the switching destination carrier may need to be indicated. In some cases, the indication may be explicit to indicate a CC1 to CC2 switch within a particular signaling, but in other cases the indication is only one UE supports PUCCH/PUSCH. May be implicit, such as when having a CC of, or the indication may be implicit, such as when a UE has only one UL SCell supporting PUCCH/PUSCH and UL PCell is not desired to be interrupted. Target Furthermore, the explicit indication may be via RRC configuration signaling or physical layer triggering, and the resulting switching and SRS transmission may be periodic or aperiodic. For example, if the UE supports only one UL CC, it is clear that the "switching from" CC should always be UL PCell. However, when the UE supports two UL CCs, when the CC to switch to is specified, it is necessary to determine the CC to switch from. In such a case, the network may configure that the switching CC should always be a SCell and the PCell never has to switch its UL transmission. This is a simple solution, which can generally minimize the interruption to PCells handling some more important transmissions (eg PUCCH). However, in some situations it may be desirable for PCell to switch as well. An example is that there can be multiple CCs to switch to, and simply relying on the SCell UL to switch to all other CCs can be inefficient. Another example is that the current RAN4 standard does not support in-band discontinuous UL CA, so both PCell UL and SCell UL can switch at the same time to avoid in-band discontinuous UL transmission, which is , PCell UL muting and SCell UL switching may be preferable. If the UE supports 3 UL CCs with 2 UL SCells (although not yet supported in RAN4), when the CC to switch to is specified, this needs to determine the CC to switch from .. In such a case, the network may set that the switching source CC should always be a given SCell and that other SCells never need to switch their UL transmissions. Alternatively, if the CC to switch to is in a group of predetermined CCs, the CC to switch from should always be SCell1, and the CC to switch to is in a group of other predetermined CCs, or Alternatively, when it is not within the first predetermined CC group, it may be set that the switching source CC should always be SCell2. Alternatively, the network may allow all CCs (or all SCells) that have UL to be switching CCs, but which of these perform the actual switching is aperiodic. Rely on network signaling such as physical layer signaling sent with SRS triggers. Furthermore, the transmission on the CC from which it was switched may be punctured or dropped, which is discussed further.

Furthermore, reduction of signaling overhead may be considered. For example, some TDD SCells may share common SRS settings (or related SRS settings) such as antenna ports, aperiodic settings, etc. That is, for some carriers having common characteristics of SRS transmission, SRS setting signaling for setting common characteristics to these carriers can be considered. This may be especially important when the UE is configured with many (up to 32) DL CCs. Designs such as multiple SRS transmissions on several TDD carriers within one subframe may be considered.

Switching may be according to network settings (periodic SRS) or network indications (aperiodic SRS that also requires RRC settings).

If this is not instructed for “switch back”, the UE may stay in the CC of the switching destination, or the UE may automatically switch back to the CC of the switching source.

One example is to explicitly indicate the switching source CC and the switching destination CC. For example, a PHY layer trigger that includes (2,4) defines a switch from CC2 to CC4. This may mean that the UE automatically returns to CC2 after switching to CC4. Alternatively, this may require (2,4,2) signaling for the round trip or (2,4) and (4,2) signaling for the round trip. The sequence of CC is (2,4,5,6) for switching from CC2 to CC4, then CC5, then CC6, or (2,4)(4,5)(5 for the same purpose. , 6). The combined switching operation can help reduce switching gap overhead. Again, the instruction to switch back to CC2 may need to be instructed or may be implicit. However, if the switchback does not require any other UL signaling, the absence of an explicit switchback to 2 means that the UE stays in the last commanded CC and performs a UL transmission. You may. In one embodiment, the switching source CC does not need to be explicitly signaled in the trigger signaling because it is implicit from the respective switching destination CC and the RRC configuration signaling that configures the switching source CC. The switching destination CC may be allowed to be set by a plurality of switching source CCs. For example, CC5 is set as the switching CC by CC2 and CC1. In that case, the order may be implicit, as CC2 has a higher priority to become the CC to switch from. Alternatively, the ServCellIndex of the CCs are compared and the one with the highest has the higher priority. However, signals with higher priority are either in use and not available, or signals that are more important than SRS (eg, PUSCH/DMRS may be considered lower priority, but PUCCH, RACH, etc.) When transporting, a lower priority CC may be used as the switching source CC. The switching CC helps reduce the trigger signaling overhead without the need for explicit signaling. However, explicit indication in trigger signaling may be supported if signaling overhead is not considered a major issue.

It may be possible for multiple CCs to be switched together at the same time. This may be indicated separately, such as (2,4) and (3,5) indicating that CC2 switches to CC4 and CC3 switches to CC5 on the same subframe. However, the preferred embodiment is to indicate ([2,3],[4,5]), which yields the same operation result, but the UE has ((2,4) and (3,5)). ) May be performed ((2,5) and (3,4)). In other words, there is the advantage that it does not refine the exact pair of CCs involved in the switch, only the original CC that is switched and the final switch result, leaving some flexibility in the UE implementation. obtain.

Switching from a CC that can support PUCCH/PUSCH causes an interruption in UL transmission on that CC. While allowing ample opportunity for SRS switching, the design has a reduced negative impact on other UL transmissions (reduced interruption duration or reduced, especially for critical UL transmissions such as PUCCH and PCell transmissions). (Interruption time, etc.) should be aimed at.

Moreover, for better sounding performance, the interference between SRS transmissions and other UL or DL transmissions needs to be better coordinated. This may also impose restrictions on the TDD UL-DL settings of the surrounding eNB.

The SCell DL state may be activated or deactivated. The deactivated CC may still send SRS, which allows the eNB to monitor the link status, but the transmission period may be longer. However, timing needs to be secured. That is, the UE may occasionally need to wake up and also send an SRS in order to maintain a connection with the deactivated CC, which may limit the TA within a reasonable range. The rising edge may be associated with a DRS transmission in DL, such as in a subframe following a DRS carrying subframe in a DRS burst, or in the next UL TXOP following a DRS carrying subframe. In other words, the SRS transmission instant is modified to be consistent with the DRS burst, including the period but possibly one subframe offset.

Alternatively, the deactivated CC skips all SRSs even if the SRS transmission on that CC is preset, since there is no DL.

When a CC is activated, it serves as an SRS trigger (MAC trigger) on that CC. In the current mechanism of SCell activation, MAC signaling is sent from the eNB to the UE, indicating the CC to be activated. MAC signaling also serves as an implicit CSI reporting trigger, requesting that the UE report CSI on n+8 and n+24/34 subframes, where n is when MAC signaling is sent. Is a subframe of. The UE may send an SRS on n+8 (including SRS switch operation if necessary) if it matches the UL-DL setting on the activated CC, or as directed by the network, Defer to the next available UL transmission opportunity. The PHY layer trigger is not needed for this operation and the transmission follows the preset settings. In other words, the MAC activation signaling can serve as a trigger for SRS switching and transmission. When multiple CCs are activated simultaneously, UE sends SRS on the newly activated CC, possibly on n+8 (and/or later subframes), without PHY layer trigger The order may be set or standardized for SRS transmission. For example, assume that the CC with the lowest ServCellIndex sends the SRS on the first SRS TXOP, the CC with the second lowest ServCellIndex sends the SRS on the second SRS TXOP, and so on. The SRS TXOP is a set of symbols or continuous symbols that can be transmitted by the SRS in consideration of the switching gap. It should be noted that the next SRS TXOP may be in the same subframe of this SRS TXOP or in the next subframe of this SRS TXOP.

The following rules may apply to handle temporary reductions in UL capability for SRS transmission. If the UE supports UL CAs for n carriers, the UE can only transmit on n-1 other UL carriers when the SRS transmission procedure is in progress (including the frequency adjustment period). One carrier needs to have a "gap" during the SRS procedure. If the UE is not UL CA capable then this will be a gap on the PCell. Gap processing may be performed when the UL data transmission is dropped (or NACKed by the network), the DL data transmission is not received (and the UE sends a NACK), and/or the network sends the first UL transmission and SRS. It may be performed when the collision with the transmission can be prevented.

Given that the SRS transmission causes the UE to exceed its uplink capability, a procedure is needed to handle the temporarily reduced uplink capability. The starting point assumption here is that the UE is configured with more UL carriers. A method for causing the UE to transmit SRS on SCell will be described below.

Case 1: UE does not support UL CA (ie only a single carrier is sent on UL at any given time). Case 1 may include one or more of the following steps/features. 1. UE is configured with one or more SCells that support uplink transmission. 2. The UE is requested to send the SRS on the SCell. 3. The UE returns from the PCell uplink to the SCell uplink (further details on switching can be found in other sections below). The UE transmits the SRS according to the provided SRS settings (in step 2 or before step 2). The UE returns from SCell to PCell. 4. The duration in step 3 is considered the "SRS gap". 5. During the SRS gap, the following may apply: (a) Any PUSCH transmission that the UE is supposed to perform is dropped and NACKed, and non-adaptive retransmissions are scheduled. (b) Any PDSCH transmission scheduled for the UE is postponed. (c) If the DRX deactivation timer and/or the DRX retransmission timer are running, they are suspended when the UE tunes away and restarted when the UE returns. The reason for (c) is that the DRX deactivation timer can expire during the SRS gap and the UE enters DRX. If there is no SRS gap, the UE may stay in the active mode by receiving the PDSCH.

Case 2: UE supports UL CA for n carriers. Case 2 may include one or more of the following steps/features. 1. The UE is configured with n or more SCells (that is, PCell+1..n..SCell) supporting uplink transmission. 2. The UE is requested to send SRS on SCell#n. 3. The UE selects the SCell k that will generate the “SRS gap”. It returns from SCell k uplink to SCell n uplink, performs SRS transmission and returns to SCell k uplink. It should be noted that SCell k can be associated with an RF chain that also supports other SCells. 4.SCell k is selected using a priority scheme with the following characteristics. (a) SCell k is chosen such that the SRS gap is triggered on the minimum number of activated carriers. (b) SCell k is selected such that the subframe in which SRS transmission occurs is an uplink subframe on SCell k, and there is no uplink transmission scheduled on SCell k during the SRS gap. (c) SCell k is selected such that the total power required after using SRS on SCell n instead of SCell k uplink transmission is not greater than the maximum allowed transmission power.

There are several considerations regarding general operating principles, requirements and designs at the subframe level.

The SRS must be transmitted on the UL transmission opportunity (TXOP) indicated by the network, eg, the UL portion of the UL subframe or the special subframe. The SRS switch must match the TDD UL-DL setting on the TDD carrier to switch to unless another TXOP has been adopted and signaled by the network. For example, for periodic SRS switching, the eNB shall ensure that SRS transmissions are not configured on the DL subframe of the CC to switch to. For aperiodic SRS switching, the network shall not trigger SRS transmission on the subframe that becomes the DL subframe of the CC to which it switches.

For aperiodic SRS transmission on CC, SRS trigger signaling needs to be used. Existing signaling and mechanisms should be generally applicable, but further extensions and reductions in signaling overhead can be considered.

Designs such as multiple SRS transmissions on several TDD carriers within one subframe may be considered. One aperiodic SRS trigger is for SRS switching and transmission on multiple CCs (predetermined order, or alternating on these CCs in the order indicated, as in SRS triggers). , There may be multiple CCs in the set.

SRS switch signaling may be combined with SRS trigger signaling. The instruction of the switching source CC and the instruction of the switching destination CC may exist in the trigger.

Moreover, for better sounding performance, the interference between SRS transmissions and other UL or DL transmissions needs to be better coordinated. Also in this case, restrictions may be imposed even on the TDD UL-DL setting of the eNB and the TDD UL-DL setting of the neighboring eNB for different carriers. As a criterion, cases with fixed TDD UL-DL settings for different carriers and neighboring eNBs should be prioritized. Otherwise, the SRS switching subframe may be restricted to a particular subframe (eg, subframe 1 after subframe 0 DL), or eIMTA adaptation may be restricted to match the SRS switching pattern. There must be. Alternatively, the switching pattern also needs to be updated with a change in the TDD UL-DL setting (an indicator is sent with the TDD reset indicator to indicate the new switching pattern). Alternatively, the periodic or aperiodic SRS transmissions on the switched CC are dropped. Alternatively, the periodic or aperiodic SRS transmission on the CC to switch to is deferred to the next available UL subframe or generally the SRS TXOP. Finally, for aperiodic SRS switching, the network may ensure consistency such that this never conflicts with TDD settings, and the UE is always assigned an aperiodic SRS switching corresponding to the aperiodic trigger. SRS TXOP shall be assumed to be supported.

There are various ways to maintain subframe level consistency. Peripheral eNBs may cooperate with each other so that the SRS is consistent between the peripheral eNBs. Peripheral eNBs may cooperate to match UL-DL patterns and/or GPs. Peripheral eNBs may coordinate and/or combine CC switching and antenna switching. It may also be useful to set the behavior of the UE. For example, the UE may not assume that it needs to perform simultaneous UL transmissions on more CCs than its UL CA capability. If the TDD SCell is instructed by the network for aperiodic SRS transmissions, the UE may interpret that UL transmissions on other SCells beyond its UL CA capability should be dropped or unscheduled. Good. If there is a collision between the periodic SRS transmission and other UL transmissions (eg PUSCH/PUCCH transmissions on other CCs), the SRS transmission will be dropped.

Within the switching subframe, it is necessary to reserve the switching time and the guard time before and after the switching operation as the case may be. This may change the subframe configuration for both the switching source carrier and the switching destination carrier. For example, to prevent the switch from affecting the next subframe of the TDD carrier, the UE switches to another TDD carrier in the middle of the subframe, sends the SRS on the other carrier, and You may switch back to the carrier some time before the end. Due to possible timing differences between carriers (especially if they are on different bands), the switchback is done during that subframe to avoid any potential impact on the next subframe. Should occur early enough. Therefore, it may not be possible to place the SRS only in the last (or even penultimate) OFDM symbol of the switching subframe. Current standards allow SRS transmission within the last 6 symbols of a special subframe, but it is desired that only the last 1 symbol of a UL subframe be extended. The next subframe may be a partial subframe if the SRS transmission is still on the last symbol of the switching subframe. Partial subframes may be in UL or DL. Partial subframes defined in eLAA may be used here. For example, the next subframe in DL may start in the second slot.

It is assumed that the time required to switch the RF from one carrier to another depends on the capabilities of the UE and the band in question. Suppose "switch 1" and "switch 2" are the durations required to perform the switch in two directions. FIG. 9 shows the SRS setting of the embodiment. As shown, the SRSs are arranged in a manner that reduces the SRS gap.

Within the SRS constellation region (determined above), the SRS symbols can be determined based on some pre-specified rule (eg, the first full symbols of the SRS constellation region).

In one embodiment, there may only be one subframe without any PUSCH/PUCCH, SRS on multiple CCs. In other words, the whole subframe may be used for some SRS TXOPs. The network dictates the switching order or SRS transmission order by one or more UEs. For example, this may instruct the UE at (1,3,4,5) for a subframe, which then switches from CC1 to CC3 and then CC4 and CC5 within that subframe. Since the switching gap is taken into account, the SRS on CC3 may be on the 4th and 5th symbols (for different RB and antenna ports on these 2 symbols) and then on the 6th to switch to CC4. And 7th, send SRS on 8th and 9th, then use 10th and 11th to switch to CC5, send SRS on 12th, 13th and 14th Switch back with. Other UEs may similarly perform the same operation. This may be combined with other embodiments such as a DL subframe as the switching CC or MBSFN on the switching CC.

The switching source operation may occur in the UL subframe or the special subframe. In the latter case, the switching can occur immediately after the DwPTS is received. That is, the switching source operation can be started at the beginning of the GP. However, the number of UL subframes and special subframes may be limited. In order to increase the opportunity for the switching source operation, the example is to perform the switching source operation on the DL subframe. If the UE does not receive a DL grant in the DL subframe, it may switch to another CC in the rest of the subframe. For this to be done, it does not require the UE to have additional capabilities such as simultaneous transmission/reception on the aggregated cells. However, if the UE has the capability of simultaneous transmission/reception on the aggregated cells as indicated by simultaneous Rx-Tx, the UE may receive DL on the CC it is switching from. Good, but it also switches its UL to another CC for SRS transmission. It should be noted that the source and target CCs are typically on different bands for this to work. The switching may be periodic or for periodic SRS transmission on the CC to which it is switching, in which case the UE may start preparing for switching even in the previous subframe (UL transmission). May not be performed, this may be guaranteed by the scheduling operation of the network). The switching may also be triggered by PHY layer signaling that the UE has received in n-4 subframes or even in this subframe, in the latter case sufficient switching gap needs to be reserved for the UE to switch. ..

The issue that needs to be addressed is the lack of UL SRS TXOPs in the CCs to switch to. Generally, the SRS TXOP is in the UpPTS of the UL subframe or the special subframe. In a large DL (DL-heavy) scenario, the number of configured UL subframes and special subframes may be very limited. There may even be a TDD CC with no UL or special subframes set. One way to provide SRS TXOP is to take advantage of the dynamic TDD (eIMTA) feature to dynamically change the TDD UL-DL settings to allow sufficient UL TXOP for the CC to switch to. It is to be. If the network or UE does not support eIMTA or does not like to use eIMTA for specific SRS switching, one solution is to indicate the specific DL subframe on the CC to switch to as MBSFN. That is. The MBSFN pattern may be pre-configured, but MBSFN can still be used for DL transmission of DMRS-based transmission if the subframe is not associated with any SRS transmission. However, if SRS switching/transmission is instructed, whether periodic or aperiodic, the network/UE performs the following: It is assumed that UE1 should switch from CC1 to CC2 for SRS on subframe n which is MBSFN. First, any UE monitoring CC2 still receives the first two OFDM symbols of the MBSFN. The UE may not detect the DL grant for that subframe and may turn off its monitoring (buffering) for the rest of the subframe (microsleep). UE1 switches from CC1 to CC2, starts transmitting SRS on the earliest possible symbol of the third symbol (immediately after the MBSFN PDCCH region) or later symbols and switches away from CC2 before the end of the subframe. The SRS does not cause any problems on that CC since the UE does not monitor the back part of the MBSFN. In order to avoid interference with other CCs in the same band, it may be useful to set MBSFN and not schedule any UE on the subframes for all these CCs. Neighboring cells may do the same unless the UE is able to mitigate eIMTA interference. Virtually all the latter part of MBSFN may be used for SRS transmission/switching. When the UE switches from MBSFN, it may need to receive the first two symbols and then switch. This may be the first SRS TXOP after x symbols (eg, x=2) if the UE cannot support simultaneous transmission/reception on the aggregated CC. Otherwise, the first SRS TXOP may be just after the first two symbols of the CC to switch to have completed. This has significant advantages over special or UL subframes as it can provide more SRS TXOPs.

UE behavior should be clearly specified by many TDD CCs set to SRS by the UE's UL CA capability. The UE shall not assume that it needs to perform simultaneous UL transmissions on more CCs than its UL CA capability. For example, if a TDD SCell is instructed by the network for aperiodic SRS transmission on subframes, the UE should drop UL transmissions on other SCells that exceed its UL transmission capacity or be unscheduled. (Or based on other rules regarding transmission priority). If there is a collision between the periodic SRS transmission and other UL transmissions (eg, PUSCH/PUCCH transmissions on other CCs), the SRS transmission may be dropped on that subframe. Moreover, proper collision handling can help reduce interruptions to other UL transmissions, especially for critical UL transmissions such as PUCCH and PCell transmissions.

For example, the SRS switch must match the TDD UL-DL setting on the TDD carrier involved in the SRS switch. In another example, the UE shall not need to perform simultaneous UL transmissions on more CCs than its UL CA capability. If the TDD SCell is instructed by the network for aperiodic SRS transmissions, the UE shall interpret that UL transmissions on other SCells beyond its UL CA capability should be dropped or unscheduled. To do. If there is a collision between the periodic SRS transmission and other UL transmissions (eg PUSCH/PUCCH transmissions on other CCs), the SRS transmission will be dropped. Carrier priorities and signaling priorities should be specified.

UE Assumptions: The UE shall not assume that it needs to perform simultaneous UL transmissions on more CCs than its UL CA capability.

One problem that needs to be solved is the timing advance (TA) of the transmission, as the UE may not have acquired the TA on the CC. This should not be an issue for in-band colocated (or QCLed) CCs, as these timings are relevant. However, UL timing may not be synchronized because there is no carrier belonging to sTAG and no active carrier in sTAG. If a CC belongs to a TAG that has an acquired TA on another CC, that TA may be used. Otherwise, the UE may not have a TA.

One approach is to ensure that the UE has UL timing on the carrier before performing SRS transmissions. Such an approach may include one or more of the following steps. 1. The UE receives a request to send an SRS on the carrier. 2. The UE checks whether it has carrier timing advance. 3. If the timing advance is now, the UE sends an SRS. Otherwise (eg, if the TA timer for sTAG has expired), the UE ignores the request to send the SRS.

Another way is that the UE needs to use some estimated TA provided by the network or perform RACH. The network identifies the sTAG's random access carrier, performs RACH to obtain timing advance, and then sends SRS on the carrier. The network may also estimate based on how long the SRS has before it is transmitted by the UE and how long the SRS resource has been allocated to the UE, which means that the network is It can help to get a better understanding of the timing and a decision as to whether or not a RACH is needed or what type of RACH is needed. One RACH should be sufficient for one TAG. Consider the case where the UE is in 3DL 1UL configuration. The second and third DL carriers belong to a timing advance group (TAG) different from the first one. The second carrier provides reference timing and random access opportunities for sTAG. Such an approach may include one or more of the following steps. 1. The UE is required to transmit SRS on Carrier 3. The request also provides the RACH preamble. 2. The UE determines that it has no timing advance for carrier 3 (eg, TA timer for sTAG has expired). 3. The UE tunes the uplink to carrier 2 and performs RACH. 4. UE receives RA response with timing advance (for carriers 2 and 3). 5. The UE tunes the uplink to carrier 3 and executes SRS transmission.

Alternatively, the UE may need to apply a sufficient time gap before and after the SRS transmission, which is necessary to avoid interference with other transmissions, the duration of the gap being the possible timing. It depends on the error, which is usually at most half the OFDM (or SC-FDMA) symbol duration, but for smaller timing errors the gap can be shorter and the SRS symbol duration is (one And between two OFDM symbol durations, etc.). This avoids RACH, but essentially couples the RACH function to the SRS transmission. For example, if the UE needs to send an SRS on CC2 without TA, but the network knows that the timing error is within half the OFDM symbol duration, then the network is The first half blank and the second half blank can instruct the UE to transmit one symbol SRS on CC2 between two symbols. The network does not schedule any transmissions on these two symbols (except for other SRS or RACH). If the time error is only 1/4 of the symbol, the blank can be only 1/4 before and after the SRS. In this case, the network may instruct the UE to transmit a longer SRS, such as 1.5 symbol duration, which provides more energy for the network to detect. However, SRS of the entire symbol duration can always be supported, even if more blanks may be present. It can also be used for multi-symbol SRS transmission, such as 0.5 blank before two consecutive SRSs and 0.5 after.

After switching from the first component carrier to the second component carrier, the UE may stop all transmissions on the first component carrier at the time specified by the command received from the network. Then, the UE may switch to the second component carrier within the transition period and transmit the signal according to the instruction received from the network. After transmission, the UE may switch back to the first component carrier or, alternatively, switch to the third component carrier according to the instructions received from the network.

In general, the cell switch command may include a current component carrier, a target component carrier, a time point at which the UE should stop transmitting on the current component carrier (eg, SC-FDMA symbol position), signaling on the target component carrier (eg, , SRS or other), transmission parameters (eg, signal format, content, resources, timing, power, etc.) for the target component carrier, and/or other switching information (eg, UE spacing). , Should switch back to the current component carrier, or should the UE switch to another component carrier after the interval, or should the UE stay on the target component carrier after the interval). As used herein, the term "current carrier" refers to the original carrier that the mobile device is transitioning to during the switch operation, and the term "target carrier" refers to the destination to which the UE is switching during the switch operation. Indicates a carrier.

FIG. 40 shows a switching method based on the SRS carrier of the embodiment. As shown, the SRS switching is performed at the carrier level, subframe level and symbol level, and D/S/U represents downlink/special/uplink subframe, respectively.

One goal of SRS switching is to reduce the number of symbol durations between the last transmission on the current candidate carrier and the first transmission on the target candidate carrier. Another goal of SRS switching is to reduce the number of switching operations and combine multiple switching operations. Another goal is to reduce the number of collisions between SRS transmissions to reduce the complexity of SRS processing at the base station and/or mobile device.

The collision may be for: 1) There are more UL transmissions scheduled on the CC than the UE's UL CA capability. 2) There are both UL transmissions and DL receptions scheduled simultaneously on the same CC. 3) Suspension time due to SRS switching in either UL or DL may cause the UE to be unable to transmit or receive. Specifically, this may not only affect sub-frames of SRS transmissions on PUSCH-less CCs, but rather next to the CC (eg PCell) to switch to during a revertive operation. Can also affect subframes of.

Therefore, if the RF switching time of the UE is >0 us and if the SRS on the CC to switch to is not transmitted early enough, the start symbol of the next subframe will be affected. FIG. 41 is a diagram of a carrier-based SRS switching scheme. SRS collisions can occur when a UE performs SRS transmission in the last symbol of a subframe and another UE needs to transmit or receive a signal in the first symbol of the next subframe. If the SRS symbol position design takes into account SRS switching time, such collisions may be avoided or at least mitigated. SRS collisions may also be caused by differences in timing advance between different UEs (eg, UEs in different TA groups (TAGs)). These SRS collisions may be eliminated or at least mitigated if the SRS symbol position considers the timing advance difference, eg, if the SRS symbol position considers the largest potential TA difference.

Another goal of SRS switching is to reduce overhead. Each SRS switching operation has a certain overhead, and frequent switching round trips can result in high overhead. Overhead may include signaling overhead, UE operational overhead, interruption, and so on. It is advantageous to reduce switching overhead. For example, one signaling for triggering more than one SRS switch or SRS transmission can be considered for the reduction of signaling overhead, so an SRS subframe allows multiple SRS switching operations and transmissions. Good.

SRS switching includes switching from one TDD carrier to another TDD carrier, switching from FDD carrier to TDD carrier, different settings (eg different ratios of uplink to downlink resources, TDD special subframes, different guard periods ( GP), etc.) may be included between the TDD component carriers.

The switching time affects the SRS subframe. For example, if the switching time is longer than the GP of the special subframe setting, it may not be possible to use the first symbol of UpPTS for SRS transmission. If the switching takes up to two symbol durations to complete, the SRS transmission on CC2 must complete at least two symbols before the next subframe starts in order for the UE to switch back to CC1. May be present, otherwise the next subframe of CC1 may be affected.

TA and timing errors affect SRS subframes. There are several situations in which a TA can influence the SRS subframe design. For example, when the UE switches from DL reception on CC1 to SRS transmission on CC2, it is necessary to secure sufficient guard time for TA of CC2 before SRS symbols can be transmitted. This guard time may be absorbed by the GP in the special subframe, but if CC1 and CC2 are in different TAGs, some time may be needed in addition to the GP. DL reception on CC1 may also be within a DL subframe (eg MBSFN subframe) and a new switching gap needs to be defined.

In another example, when the UE switches from UL transmission on CC1 in TAG1 to SRS transmission on CC2 in TAG2, the TA difference between TAG1 and TAG2 needs to be taken into account and on CC2 There may need to be a guard time before or after the SRS symbol, otherwise some transmissions/receptions may have to be dropped. If timing errors are present (such as due to timing deviations in the UL when closed loop timing adjustments for UL transmissions are not used or are not used for a period of time), the largest possible timing error is the switching gap. May need to be added to.

The SRS subframes of one embodiment may include more symbol positions for SRS transmission on the target carrier. In order to avoid affecting any potential transmission/reception on the next subframe, the SRS on the target carrier can be transmitted on symbols that were not previously assigned to the SRS. In some embodiments, unoccupied symbols (eg, data, control, etc.) in the target carrier may be assigned to carry SRS transmissions.

More than two symbols (eg, between two and eleven symbols) are UL subframes on the target carrier if RF frequency matching and TA difference result in two symbol gaps for SRS switching. May be assigned to carry SRS transmissions within. Similarly, all but the last two symbols in the UpPTS (including additional SC-FDMA symbols in the UpPTS) of the special subframe, and symbols 4-11 in the DL MBSFN subframe are on the target carrier. Can be used for SRS transmission. If more symbols are acceptable for SRS transmission on the target carrier, it is more likely to reduce the number of interrupted subframes due to SRS switching. In other words, for the target carrier, the switching time, the timing error, and the first and last gaps to absorb the TA make the subframe an SRS subframe and all intermediate symbols potentially to SRS transmission. Can be used.

The SRS subframe of an embodiment may have multiple SRS switching operations and SRS transmissions for the UE. To help reduce the overhead due to SRS switching, multiple SRS switching and SRS transmissions can be performed consecutively within one subframe. This is made possible by allowing more SRS symbols on the target carrier.

FIG. 42 shows an example of multiple SRS switching and transmission, all done in one subframe and each operation requires two symbol durations. It should be noted that more than one SRS transmission can occur on the target carrier (eg, due to different antenna ports and/or different transmission bandwidths). On the other hand, if the switching operations are separately configured or instructed and performed separately, multiple subframes need to be used for SRS switching, resulting in higher overhead.

To avoid interference between SRS and other signals, SRS subframes may not be scheduled with other transmissions in the cell (first in the case of MBSFN subframes used as SRS subframes). 2 symbols, and DwPTS in the case of special subframes used as SRS subframes). Alternatively, if other transmissions in the cell should be allowed in the SRS subframes, these may be TDM'd with the SRS transmissions, shortened PUSCH (partial start subframe and/or partial End subframes may be used) or truncated PUCCH-like truncated transmissions.

There are several examples of switching subframes.

One example is that the target carrier subframe is a special subframe. If the target carrier subframe is a special subframe, all UpPTS symbols may be used for SRS transmission (subject to the switching gap). However, there are special subframe settings that have an UpPTS of only one symbol and do not allow further symbols to be used for UpPTS (eg, a special subframe setting 4 with a DwPTS of 12 symbols), In this case, the special subframe may not be suitable as the target carrier subframe, so the next two examples described below need to be considered.

One example is that the target carrier subframe is a UL subframe. If the target carrier subframe is a UL subframe, then all symbols may be used for SRS transmission (subject to switching gaps). The PUCCH (including the shortened PUCCH format) or PUSCH on the carrier may not be transmitted on this subframe by any UE in the cell unless the SRS occupies a small number of symbols. For example, if the switching gap and SRS transmission occur in the second slot of the SRS subframe, other UEs in the cell may still be scheduled to transmit in the first slot of the SRS subframe. Alternatively, if the switching gap and the SRS transmission occur in the first slot of the SRS subframe, the other UEs in the cell may still be scheduled to transmit in the second slot of the SRS subframe. .. If partial PUSCH and/or PUCCH should be supported, the appropriate indication from the network should be provided, so that the UE sending the PUSCH/PUCCH will receive one of the PUSCH/PUCCH transmissions accordingly. You can puncture more than one symbol. Puncturing a symbol in a transmission means that the punctured symbol is not transmitted, or is otherwise a null symbol (e.g., transmitted at a power level of 0 on one or more resources allocated to carry the transmission). Transmitted symbols). The resource on which the symbols are punctured may be a priori information for the base station and/or the UE. In one example, the PUCCH transmission is scheduled to be transmitted in the same subframe as the SRS transmission, and the PUCCH transmission is one of the PUCCH transmissions that may overlap the symbols of the SRS transmission or otherwise collide. It may be shortened in the time domain by puncturing the above symbols. However, it may also be possible to configure all SRS transmission bandwidths to be limited to PRBs that do not overlap in the PUCCH region. For example, the bandwidth includes 100 PRBs for a cell, but eNB configures all UEs associated with the cell in PRBs that are not greater than 94, if none of the PRBs are in the PUCCH control region, from different UEs. PUCCH and SRS are orthogonal in frequency and may be sent simultaneously by different UEs (the same UE should not send PUCCH and SRS on overlapping symbols even if they are orthogonal in frequency) .. Therefore, the UE may assume that, in such SRS subframes, the SRS from either UE does not collide with the PUCCH in the frequency domain, and the UE sends the SRS and PUCCH on duplicate symbols. It is not expected (drop will be adopted if this happens).

SRS switching may collide with DL reception. For example, this may affect the symbols after the DwPTS (or even the DL subframe due to subframe boundary mismatch for different bands). In this case, the PDSCH overlapping symbols are punctured. SRS switching is not allowed to affect the control area of the DL or, alternatively, the entire DL transmission in the subframe is dropped. In one embodiment, the UE assumes that symbols/slots/subframes that partially or completely overlap with the SRS switch should not be used for UL or DL transmission with network scheduling.

For example, if the first symbol of the UL subframe is affected due to SRS switching, the existing shortened PUCCH format shifts in the PUCCH time domain but may be reused at the same or shifted RS positions. ..

FIG. 43 is a diagram of a carrier-based SRS switching scheme. As shown, if the SRS switching of the UE collides with the starting symbol in subframe n+1, the shortened PUCCH carrying the A/N for subframe nk is affected in n+1. Not sent on the symbol.

For shortened/punctured PUCCH, the punctured symbols are up to DMRS symbols, ie, DMRS symbols should not be punctured. If there is a potential overlap between the DMRS symbol and the SRS switch, the priority/drop rule applies. For the PUCCH format with x symbols before the first DMRS or after the last DMRS, up to x symbols can be punctured. Puncturing may result in non-orthogonality if orthogonal cover codes (OCCs) are used for UE multiplexing. There are several examples of this. One is to rely only on cyclic shift and FDM for orthogonality, and OCC is not used for orthogonality. For example, with normal CP and delta_shift=2, ACK/NACK from 18 different UEs can be multiplexed in format 1a/1b. With more RBs for PUCCH, capacity should not be a big issue. Appropriate settings for delta_shift and PUCCH RB numbers can be useful. The other is to configure all UEs with the same punctured PUCCH (with the same number of punctured symbols) to be on overlapping PUCCH RBs and the OCC Used according to the PUCCH data symbol. For example, if 3 data symbols are left in the slot, a length 3 OCC is used, and at most 3 UEs can be orthogonally multiplexed using the OCC. If two data symbols are left in the slot, then a length-2 OCC is used. This is similar to the shortened PUCCH format 1a/1b which can be reused if the first symbol is punctured.

In order to maintain OCC orthogonality due to puncturing, the eNB may set a larger PUCCH region with respect to the PUSCH hopping offset, so that more RBs may be used for PUCCH. The UE may then appropriately select n_CCE (or other UE specific parameters) for DCI, which allows UEs with different numbers of punctured PUCCH symbols and different PUCCH formats. Use a different PUCCH RB. Alternatively, each mixed format region may be used for one type of punctured PUCCH. Unused RBs may also be used and eNB settings/instructions may be needed for this purpose.

The Ack/Nack iteration may also be set by the eNB with an iteration factor of 2. Iteration may be used only when collision with Ack/Nack occurs. That is, no repetition is used for subframes not affected by SRS switching, Ack/Nack is repeated for subframes affected by SRS switching, or, in effect, the next Ack/Nack. Delay until the opportunity. The next Ack/Nack opportunity may bundle the delayed one from the previous opportunity with the one for this opportunity.

One example is that the target carrier subframes are DL subframes. If the target carrier subframe is a DL subframe, it should be an MBSFN subframe and the PDSCH should not be scheduled. All symbols may be used for SRS transmission (subject to switching gap). The use of DL subframes for SRS transmission may help reduce UL resources and may help reduce collisions with PUCCH.

On the other hand, there are examples of subframes that are switching origins. One example is that the target carrier subframe is a special subframe. If the current carrier subframe is a special subframe, the UE may start switching away immediately after DwPTS. If the GP is long enough, the UE may switch back to this carrier for the next subframe or for one or more SRS transmissions on this carrier in UpPTS. However, when the DwPTS is long, this subframe is not suitable to be the switching source subframe when it affects the next subframe.

One example is that the target carrier subframe is a UL subframe. If the UL subframe is not scheduled with any UL transmission, this subframe may be the switching source subframe. Switching away can start immediately after the previous subframe or immediately after the SRS is transmitted on this carrier. After the UE switches back to this carrier, one or more SRS transmissions may be performed if there are one or more symbols left in this subframe.

One example is that the target carrier subframes are DL subframes. If the DL subframe is an MBSFN subframe and is not scheduled with any PDSCH, this subframe can be the switching source subframe. Immediately after the PDCCH region, the UE may start switching away from this carrier.

It should be noted that switching for SRS transmission in UL can cause DL interruption. The DL break may be due to RF frequency tuning in UL switching, in which case the DL break caused by UL frequency tuning is no longer than the RF frequency tuning time (eg, 2 symbols). This may be the case if the UE has a single RFIC or an implementation with strongly coupled transmit and receive chains. DL interruption due to UL tuning may occur if the UE reports that an interruption is required for CA operation (eg CA activation/deactivation etc.), otherwise UL tuning DL interruption by does not occur. Alternatively, it may be the RF tuning time and the UE capability reported to the network, which reflects whether DL interruptions occur during RF tuning. For SRS transmission on the target carrier, DL may also be interrupted during transmission if the UE cannot receive and transmit at the same time in the aggregated cell. MBSFN An interrupted DL symbol or subframe, such as occurs in the blank part of an MBSFN subframe, needs to be processed. If there are multiple possibilities of which carrier is suspended in DL, it is necessary to specify the DL carrier of suspension. The suspended DL carrier may be considered as a switching source CC for SRS switching. For example, if switching occurs within subframe n, subframe n+1 is affected, and subframe n+1 is a DL subframe, then either CC1 or CC2 is selected as the affected DL subframe. May be done. The network can set or dictate which should be selected.

The aforementioned current carrier subframe type and target carrier subframe type can be combined. In typical operation, the current carrier subframe type and target carrier subframe type are the same, but with FDD+TDD CA, inter-band CA, etc., other cases are more likely. It should be noted that when both source and target carriers are considered, the SRS transmit symbol position is not only affected by the subframe type, but also by the RF IC architecture of the UE. For example, less symbols may be used for SRS transmission if the UE's transmission and reception are done by one RF chain or they are tightly coupled, otherwise more symbols are used. It may be used for SRS transmission. These are shown in FIG. Some more details are given below.

FIG. 44A shows a case where the UE switches from CC2 to CC1 for SRS transmission on CC1 in the SRS subframe. Both carriers are special subframes. The UE is assumed to have a single RF design, which combines transmission and reception on CC. It is also assumed that the special subframe settings are consistent, that is, the DwPTS and UpPTS durations are the same for CC. In this case, the UE needs to monitor the DwPTS in the DL, and starts switching after the DwPTS ends. However, if the UE does not detect the PDSCH scheduled for the subframe, the switching may be started immediately after the control region ends. For example, if the control region has 2 symbols but the DwPTS has 3 symbols, the UE does not detect any grant for PDSCH and if it recognizes that it needs to switch to CC1, the second You may start switching from the symbol (counting from 0). However, the DwPTS may include more CRS after the control region. In conventional systems, the UE may or may not monitor these CRSs in the absence of PDSCH. This may be retained, but a better way may be to allow the UE not to monitor these CRSs so that the switching can occur earlier in time. Even if the DwPTS has, for example, 9 symbols, the network may configure the UE to send the SRS on symbol 4 of CC1, while the control region is symbols 0 and 1. Across, the UE needs two symbols to switch. This means that the UE should not assume PDSCH grant and can ignore all CRS after the control region, but switch to CC1 immediately after the control region. Another alternative is that if the UE is configured to send SRS on CC1 on a sufficiently early symbol (e.g. symbol 4), the UE does not include a grant for that subframe to detect, It may be assumed that the CRS on CC2 also need not be monitored. In that case, the eNB does not send any information to be received in the subframe to the UE. There may also be cases where the eNB sends out an aperiodic SRS trigger in a few subframes before the UE schedules SRS transmissions on CC1 and the UE may behave similarly. If the same subframe trigger is used, the UE should detect the PDCCH in the control region, if such a trigger is found, no other DL reception is assumed and the UE moves away from CC2. You can switch immediately. It should be noted that there may be some time for the UE to seek the trigger and detect the PDCCH, so the eNB shall not trigger SRS transmission on symbols that are too early for the UE to transmit. Is. For example, if the control region has two symbols and the UE needs one symbol time to detect and decode the PDCCH (if UE capabilities are known to the network), the fastest switch occurs at symbol 3. , And a faster SRS transmission can occur with symbol 5 on CC1. After the switching, the UE may start SRS transmission for each setting and instruction including the symbol position. It should be noted that there may (or may not) be a gap in the symbol prior to the signaled SRS transmission. There may be one or more SRS transmissions on CC1 and the UE is signaled to switch to another CC for SRS transmission if there is sufficient time left in the subframe. May be. Finally, the UE may schedule to transmit the SRS within the UpPTS on CC2 (on one or more symbols), so the UE switches back to CC2 and transmits. Similar concepts and procedures can be adopted if carrier switching is also performed to support RACH transmissions.

A similar embodiment may be used in Figure 44B, where the special subframe settings are different for CC1 and CC2. However, in any case, the UE may switch away from CC2 after completing DL reception. The various embodiments described above can be employed in this case. Needless to say, if there is not enough time left on CC2 in UpPTS, SRS transmission on CC2 should not be performed as shown in the figure.

In FIG. 44C, the same settings are assumed as in (a), except that the UE is assumed to have separate/separate transmit and receive RF designs, whereby the UE is scheduled for UL on CC2. You can switch the transmission from CC2 to CC1 at any time, as long as you don't. Therefore, in the figure, the UE still receives the DL for the entire DwPTS, but the UL is switched to CC1 even before the DwPTS ends. If the UE recognizes that SRS switching should occur in this subframe, the UE may switch UL even earlier. For example, if SRS transmission on CC1 is configured, the UE can switch even before the subframe starts. In another example, the DwPTS region may span 10 symbols, but the UE detects the trigger for SRS transmission based on the PDCCH in symbols 0 and 1 and detects the DCI in symbol 2 and The decoding can be completed and then switching can be started on symbol 3 while DL reception is still in progress to symbol 9. However, in this case the UE needs to report its RF capabilities, such as being able to receive and transmit at the same time in the aggregated cell.

FIG. 44D shows an example similar to (c), but the special subframe settings are different for CC. Similar embodiments can be employed.

FIG. 44E shows an example of switching from a UL subframe to a UL subframe. CC2 cannot schedule the SRS transmission of CC1 and any UL transmission that overlaps the switching time. However, SRS and shortened PUSCH may be transmitted on CC2 on non-overlapping symbols (see FIG. 44F for an example).

FIG. 44G shows an example of switching from a DL subframe to a DL subframe. Both subframes are set as MBSFN. Some other cases are shown in Figure 44K, but this is not meant to be exhaustive. The embodiments described above apply wherever appropriate and combinations of these can be made.

The subframe of the switching source and/or the switching destination may also be the DRS subframe or immediately after the DRS subframe, especially when the carrier is in the deactivated mode or the UE is in the DRX.

A similar design is used when RACH is sent.

From an efficiency point of view and a feasibility point (in terms of currently supported SRS symbol positions), the switching gap affects the SRS subframe.

For example, if the switching gap (eg, 900 us) is longer than the duration of GP and UpPTS in the special subframe setting, it may not be possible to use any symbol of UpPTS for SRS transmission. In this case, the next subframe, which is typically a UL subframe, should be used for SRS transmission. Obviously, relying only on the last symbol of the currently supported UL subframes is by no means efficient.

In another example, if the UE switches from CC1 to CC2 for SRS transmission on the last symbol of the UL subframe and if the switching gap takes a non-zero time to complete, the UE switches back to CC1. Sometimes the next subframe of CC1 is affected. If it is desirable to reduce the number of subframes affected by SRS switching, then the SRS transmission opportunities supported by current UL subframes are insufficient.

In yet another example, if the switching gap is long, e.g., 500 us or more, the reverting operation on the special subframe is the next subframe even if the SRS transmission is on the first symbol of UpPTS. Affect.

In short, it can be seen that the current SRS symbol position in the special subframe or UL subframe is insufficient if all RF switch duration values are supported in the standard. There are two alternative options:
Option 1: Add more SRS transmission opportunities or Option 2: Support all RF switching durations provided by RAN4.

If Option 2 is determined, some RF switching durations provided by RAN4, eg, 500us, 900us, are not supported at least in Rel-14, but future releases may provide support for these.

Alternatively, if option 1 is determined, RAN1 needs to standardize new SRS transmission opportunities in addition to up to 6 symbols in the UpPTS and the last symbol in the UL subframe. The rest of the contributions provide further details for this option.

Option 1 needs to support all SRS switching gaps. Inevitably, SRS switching operations span more than one subframe, especially for long switching gaps. For efficiency, it is preferable to allocate multiple consecutive subframes for SRS switching. For example, one complete SRS switching operation (from switching from CC1 to switching back to CC1) can include a special subframe, the next UL subframe, and possibly one or more further subframes. .. The UE may perform multiple SRS transmissions on one or more TDD CCs in these subframes. It should be noted that these TDD CCs may be in one band and there may be no switching gap between SRS transmissions on these TDD CCs.

Next, we consider the options for timing advance for SRS on TDD CC without PUSCH.

The UE may have a TDD CC with more PDSCHs than a TDD CC with a PUSCH. With proper network settings and instructions, the UE can perform a switch to any TDD CC and send SRS on that CC. One issue that needs to be resolved is the Timing Advance (TA) of the transmission, as the UE may not have obtained TA on its CC. It should be noted that in previous releases CC without UL may not be set in any TAG. Any CC that supports SRS transmissions must be set in the TAG, at least for SRS switching purposes. To do this, the eNB needs to configure the UE with TAG and add the indices of all CCs that support PUSCH/PUCCH/SRS/RACH to the corresponding TAG.

There are two main cases to be considered:
1) If the CC belongs to that tag on another CC of the TAG with a valid retrieved TA, the TA may be used as already defined in the standard.
2) If a CC belongs to that tag on any CC of a TAG that does not have a valid TA retrieved, there are again two cases:

a) At least one CC in TAG supports PUSCH. In this case, the reason the TAG does not have a valid acquired TA may be that there is no RACH or TA update in the extended period. The RACH on the CC with PUSCH can then be used to obtain the TA, or the current TA update mechanism can be used on that CC. The network should ensure that a valid TA is available to the TAG before the SRS switch to a CC without PUSCH in the TAG. For example, before the eNB sends an SRS trigger for CC, the eNB needs to make sure that the UE has a valid TA for the associated TAG. Therefore, from the UE's point of view, the UE may assume that the eNB does not send an SRS trigger for a CC that does not have a valid TA associated with the CC's tag. One embodiment is that when the UE receives activation signaling for the CC in the TAG that is deactivated with PUSCH and RACH (possibly on the second CC), the UE should send the RACH. Is. This RACH may be non-contention based and the time frequency resources for the RACH may be indicated in the activation signaling. Alternatively, the UE should not send the SRS and the UE may send a request (e.g., scheduling request) to the eNB to request the RACH on the CC that supports the RACH in the TAG. ..

b) CC in TAG does not support PUSCH. This is the main focus of this contribution. There are several options:

i) Option 1: Insert RACH on one of the CCs in TAG.

This requires standard changes, including: First, the standard should allow the UE to be configured with RACH on more CCs than its UL CA capability, but PUSCH is not configured on these CCs. Pre-configure transmission resource/preamble code group for new RACH and use PDCCH on current carrier to trigger transmission of preamble code in these pre-configured resources on destination carrier Should be considered. Second, collisions between RACH on CC without PUSCH and other UL transmissions on other CCs may occur if these UL transmissions exceed the UE's UL CAP capability, Therefore, the collision handling for the newly introduced RACH needs to be provided. Collision handling is similar to SRS collision handling, but RACH may have a higher priority than SRS to ensure that timing is available. In general, RACH may have higher priority than other UL transmissions, except PUCCH carrying ACK/NACK. Alternatively, the RACH may follow the same priority as the aperiodic SRS switch. Third, this RACH may be non-contention based and may be used to obtain timing advance on carriers that do not include the physical uplink shared channel (PUSCH). Fourth, a shortened RACH preamble format 4 may be used, possibly allowing for carrier switching times of 2-3 symbol durations. Since RACH also complies with the switching time limit, it may take a few symbols for the UE to switch the TAG for RACH transmission and then switch back within the other two symbols. If a shortened RACH is used in UpPTS, the next subframe may be affected and the UE cannot receive DL on the revertive carrier or cannot send in UL. In that case, the next DL may be a partial subframe, or the next subframe may be a UL subframe that does not schedule any UL transmission on the switching-back carrier by the eNB. .. In other words, if RACH with a shortened form should be performed in UpPTS, the next subframe may be a UL without any scheduled transmission on the carrier. A similar concept can be adopted for regular RACH. Alternatively, the network may instruct the UE to transmit the RACH in at least two symbols (or other suitable number based on the required switching time) before the subframe ends. This is because the shortened RACH is shifted away from the last two symbols of the special subframe (the RACH symbol position should be set and/or indicated) and the normal RACH is shortened in the time domain. And leave enough gap before the end of the subframe. An untruncated RACH format (eg format 0) can also be supported if the switching time plus the transmission time fits within the subframe. For format 0, the RACH transmission time is about 900us, so switching less than 40us should work, other subframes are not affected. For one TAG, one RACH on the carrier in the TAG is sufficient. If the SRS transmission in the TAG keeps the UE updated by TA adjustment, then RACH is not needed thereafter. Therefore, such a RACH may be only the initial RACH after the TAG is activated after the serving cell is set or after the deactivation or the long DRX. However, this is usually acceptable even if the RACH can collide with the transmission/reception of other subframes, since the RACH is usually only needed once for the TAG, in these cases the RACH is It has a higher priority and other transmissions are dropped. The network should be knowledgeable in advance and may be scheduled accordingly to avoid drops. The UE may assume that no other transmission/reception will occur if it collides with the RACH.

For RACH configured on TDD CC without PUSCH, UE needs to perform carrier switching. If the UE supports more than one CC, the switching source CC needs to be specified in the RRC configuration for the RACH or the DCI for triggering the RACH. For periodic SRS, it is preferable to set the switching source CC in the RRC setting. For the aperiodic SRS, the CC to switch from may be set in the RRC configuration or, alternatively, may be specified in the PDCCH order to trigger the RACH. Alternatively, if by default the UE supports only two UL CC CAs, the CC from which the RACH is switched to is always a UL CC that is not associated with a PCell, ie the PCell UL is not affected. An example is that CC1 is the switching source carrier, while CC2 is the switching destination carrier. A new RACH transmission may be set up and/or indicated at CC1, message 1 is sent at CC2, followed by message 2 response at CC1 or CC2.

Therefore, the network has new settings such as the specified CC to switch from, the specified inter-carrier scheduling of the RACH, the specified RAR content, etc. for only one CC in the TAG group without PUSCH. Allows to configure RACH based on non-contention on CC without PUSCH. RACH format 4 is supported and should be shifted earlier for UEs with non-zero switch times so that the next subframe is not affected. The collision handling either reuses the existing one for RACH or follows the rules for SRS switching.

TA adjustment via TA MAC CE can be done based on SRS transmission. Current support can be used as a basis. Inter-carrier indication of TA commands may need to be supported. For example, the TA command applies for CC2 (or more generally, a tag with CC2) but may be carried on CC1.

ii) Option 2: UE estimates TA.

The UE has a TA for TAG1 (related to the propagation delay between the UE and the cells in TAG1) and a TAG1 and TAG2 (related to the propagation delay difference to the cells in TAG1 and the cells in TAG2). The TA for TAG2 can be estimated based on the DL arrival time difference of. The time synchronization error between TAG1 and TAG2 introduces some error to the TA estimation for TAG2, but for TDD cells that serve the same UE, the time synchronization error is small (eg <500ns).

In that case, the UE transmits the SRS, for example, on symbol n after switching to CC with the estimated TA. However, due to the estimation error in TA, the SRS may partially overlap with the previous (symbol n-1) and subsequent (symbol n+1) symbols. Again, there are several cases.

a. In some cases, except for SRS, if the eNB does not schedule other UEs on the CC, the SRS symbol position may be in the middle of the SRS subframe, as described above, so that the overlap is on any PUSCH/PUCCH It has no effect.

b.If the eNB schedules other UEs for SRS transmission on symbols n-1 or n+1, the SRS transmissions from the UEs partially overlap in time, but the SRS has a comb structure in the frequency domain. Both SRS transmissions can be detected by the eNB because they are repeated (ie, redundant) in the time domain relative to. Nevertheless, the overlap causes some degradation of the received SRS, so it is up to the eNB to determine whether SRSs from other UEs can be scheduled.

If c.eNB schedules another UE for SRS transmission on symbol n, SRS transmission from the UE is such that one uses cyclic shift 0, the other uses cyclic shift 4, It should have cyclic shifts away from each other.

To summarize this option, the UE can estimate the TA on the CC to which it is switching and send the SRS. A suitable eNB implementation can ensure that the SRS is detected by the UE. This option does not require standard impact, but may require some RAN4 testing of the UE's TA estimation.

iii) Option 3: The UE estimates TA and applies extra guard time.

This is similar to Option 2, but the UE leaves some gaps as guard time for SRS transmission, so that the SRS overlaps with the symbol before or after it, even with some TA estimation error. do not do. Therefore, if symbols before or after SRS transmission are scheduled for other transmissions, there is some problem. To do this, the effective SRS transmission in the time domain is shortened or two symbols are combined for one SRS transmission in the middle of the two symbols. This option requires some standard changes.

The DL timing difference between the TAGs is significant, for example greater than a few microseconds between the FDD TAG and the TDD TAG but up to about 32us, and the UE recognizes only the FDD TAG TA but the TDD TAG If we are not aware of the TA, relying purely on the UE's UE estimate for the TDD TAG can result in larger errors. However, such an error is limited by twice the DL transmission time difference plus the propagation time difference. This is typically limited by one symbol duration. If the eNB can blank one symbol before and one symbol after the SRS transmitted symbol by the UE, there is no collision/interference and the eNB can rely on a search in the time domain to recover the SRS. This is similar to the variable duration RS design described in U.S. patent application Ser.No. 14/863,382 entitled "Device, Network, and Method for Communications with Variable-duration Reference Signals", which is the entire content of this. Is incorporated by reference as if reproduced. Alternatively, the eNB can signal the UE about the DL timing difference between the two TAGs. The signaling may be in the form of TA or TA coordination. In other words, the eNB may not have received any signal (RACH or SRS) on the TAG from the UE, but may still send TA signaling for the TAG to the UE and the TA command is actually the TAG's Between transmission timing differences (possibly with other minor adjustments provided by the eNB). Alternatively, the network can set the TA for a TAG that does not have any PUSCH/PRACH/PUCCH, which reflects the transmit timing difference between the TAG and the PCell TAG. On the UE side, this receives the TA, which is a relative value to the PCell TA. Alternatively, the TA set in the UE may be relative to the TAG DL reference timing, in which case the UE should adjust its TA relative to the TAG DL reference timing. The UE may estimate and report the DL reception timing difference to the eNB. This may use the difference to estimate TA by TA2=TA1+delta_DL-delta_Tx, where TA1 and TA2 are TAs of the first and second TAGs, and delta_DL is DL reception timing difference (TAG2 DL reception time minus TAG1 DL reception time), and delta_Tx is eNB DL transmission timing difference (TAG2 DL transmission time minus TAG1 DL transmission time). Such a formula may also be used by the eNB if all the information is available.

Next, we discuss periodic SRS and aperiodic SRS designs. It is generally accepted that aperiodic SRS transmission provides the highest flexibility for the network to obtain channel quality information based on sounding. Therefore, a switch to a TDD carrier without PUSCH may occur to perform the aperiodic SRS transmission.

Aperiodic SRS is configured via RRC signaling and dynamically triggered via DCI format 0/1A/2B/2C/2D/4 for TDD and 0/1A/4 for FDD. The configuration and DCI may be extended to support SRS transmission based on carrier switching. For example, the DCI may direct SRS transmissions on one or more carriers, including those without a PUSCH. Therefore, the carrier ID associated with the SRS transmission may need to be included in the DCI. If the SRS symbol position needs to be indicated (eg, for a particular SRS transmission, the SRS transmission starts at symbol x and ends at symbol y, or starts at symbol x and continues for z symbols) , Such information can be included in the DCI. The DCI may schedule other transmissions or receptions for the carrier receiving the DCI or other carriers, but the scheduled carrier may be the same as the triggered carrier for the SRS transmission, or different. May be. If the indicated SRS transmission collides with other transmissions indicated by the same (or different) DCI, a collision handling mechanism is provided. Even if the timing relationship between SRS triggered switches is changed to avoid collision with the same DCI used for both SRS switch trigger and Ack/Nack from scheduled UL or scheduled DL Well (shifted to next SRS transmission opportunity, etc.) or DCI for SRS triggered switching requires another DCI.

The carrier ID associated with the SRS transmission may need to be explicitly or implicitly specified (via association with one of the multiple parameter sets configured via RRC signaling) in the DCI. .. This means that inter-carrier triggering for aperiodic SRS can also be supported. More specifically, the DCI sent on CC1 may be used for inter-carrier scheduling of data for CC2 and inter-carrier triggering of SRS transmission on CC3.

Regarding the number of parameter sets set for aperiodic SRS transmission, the current specification supports up to 3 parameter sets via 2 bits in DCI format 4. It may be considered that one more bit is added if the 2-bit trigger runs out. On the other hand, for each DL CC (including each FDD CC when aggregated), there can be up to 3 configured parameter sets, which is sufficient for the total available for aperiodic SRS. It can result in multiple parameter sets. It should be noted that DCI sent on FDD carrier may also be allowed to trigger SRS transmission on TDD CC without PUSCH. In other words, two options may be considered, either increasing the number of SRS required bits or supporting carrier-specific SRS parameter set settings. Similar to the introduction of carrier-specific SRS parameter sets that do not have explicit bits in the DCI and utilize the carrier dimension to carry more information about the parameter set selection, other for this purpose Dimensions may be used as well. For example, if the trigger is sent within a DL grant, the indication is associated with a group of parameter sets for DL grant. Otherwise, if this is sent within UL authorization, one of the other groups in the parameter set is indicated. Similarly, it can further utilize the DCI format dimension, 0/1A/2B/2C/2D/4 for TDD and 0/1A/4 for FDD, where each format for each TDD/FDD setting is format specific. Parameter set of The subframe number (or slot number) or subframe type (DL or special subframe) in the radio frame may be used as well. For example, both the trigger sent in subframe 0 and the trigger sent in subframe 1 may result in an SRS switch in subframe 6, but if the former is used, the UE may use the first parameter set. , While the latter uses, the UE uses the second parameter set.

The switching source CC may need to be specified for each transmission. One method is to specify the CC to switch from within the RRC setting of the parameter set. The other way is to specify it in the DCI trigger. The former has less physical layer signaling overhead, but is less flexible than the latter. RAN1 can consider the pros and cons and decide which is supported.

Due to the enhanced efficiency, the SRS switching operations for some SRS transmissions can be set to be continuous in time (subject to the SRS switching gap). This is because aperiodic SRS supports multiple consecutive SRS transmissions (on the same or different CCs), higher layer signaling configures one or more SRS configurations at a time, and DCI triggers one at a time. It is necessary to trigger the above SRS transmission. For example, the first SRS setting is for SRS transmission on TDD CC1 in OFDM symbol k, the second SRS setting is for SRS transmission on TDD CC2 k+1, and Similarly, if the relevant bit is set, the UE performs carrier switching multiple times and sends the SRS accordingly on the designated CC.

Such information can be included in the DCI if the SRS symbol position needs to be indicated.

If the indicated SRS transmission collides with another transmission indicated by the DCI within a subframe (eg, subframe n), a collision handling mechanism should be defined. For example, in subframe n+4, ACK/NACK for DL transmission in subframe n needs to be transmitted, and other UL transmissions (eg, PUSCH, CQI feedback) are in DCI in subframe n. Need to be transmitted in subframe n+4 according to In this case, the SRS transmission associated with the SRS trigger in subframe n should not occur in subframe n+4. This may be postponed to the next SRS transmission opportunity until no DL or UL grant is sent to the UE in subframe n. Several alternatives may be considered. First, the SRS transmission may be deferred to the next aperiodic SRS transmission opportunity, which is associated with the operation (for transmission or reception) coordinated by the eNB. It may or may not be present, or the next aperiodic SRS transmission is always associated with an UpPTS that cannot send an ACK/NACK. Second, the DCI for SRS switching may not be associated with other scheduled DL/UL transmissions. Third, in the case of FDD+TDD CA, FDD and TDD may have different timing relationships, so DCI for SRS in FDD CC may not collide with subsequent UL transmissions. Good. Fourth, different HARQ timings for other scheduled transmissions in the SRS trigger may be defined. If the aperiodic SRS switching is limited to the special subframe UpPTS (eg, forming an SRS switching pattern with a period of 10 ms or an SRS switching pattern with a period of 20 ms), this is especially a potential for Ack/Nack. Many collisions can be avoided. In this case, the periodic SRS and the aperiodic SRS have the same operation, and the trigger may be omitted. Alternatively, the trigger further provides information for periodic SRS (eg, SRS parameter set selection). Therefore, it is necessary to specify the SRS transmission opportunity (subframe position and symbol position).

Periodic SRS is supported in Rel-8 to LTE as the primary means for uplink sounding. Although periodic SRS is considered less flexible than aperiodic SRS, periodic SRS is associated with smaller signaling overhead than aperiodic SRS, and because of its predictability of occurrence, it has collision avoidance It can be easier for processing. With proper settings, periodic SRS can be used more efficiently than aperiodic SRS in certain scenarios. Further, the periodic SRS may be configured with a relatively long period (eg, 20 ms or more, especially if the switching gap is long), and/or may be associated with a lower priority during the collision, thereby , The periodic SRS switching may not affect other transmissions. Configured SRS transmissions should also avoid certain subframes such as subframes 0 and 5. Therefore, periodic SRS transmissions may be used for switching based on SRS carriers.

The setting of periodic SRS can use the existing mechanism and signaling as a reference. Due to the enhanced efficiency, the SRS switching operations for some SRS transmissions can be set to be continuous in time (subject to the SRS switching gap). This requires that the periodic SRS settings allow multiple consecutive SRS transmissions (on the same or different CCs) and that higher layer signaling sets one or more SRS settings at a time. For example, the first SRS setting is for SRS transmission on TDD CC1 in OFDM symbol k for bandwidth setting 1 and the second SRS setting is OFDM symbol k+1 for bandwidth setting 2 For SRS transmission on TDD CC1 in, and so on. That is, multiple consecutive SRS transmissions on the same CC may be for different bandwidth settings, antenna ports, etc. Multiple consecutive SRS transmissions on some CCs may also be considered. For example, the first SRS setting is for SRS transmission on TDD CC1 in OFDM symbol k, the second SRS setting is for SRS transmission on TDD CC2 k+1, and The same is true.

The SRS transmission opportunity (subframe position and symbol position) needs to be set for the periodic SRS, and the setting should consider the switching time to reduce the effect on other transmissions. For example, if the switch time is non-zero, the set SRS symbol position should avoid the last symbol of the subframe.

The problem with periodic SRS is that if the SRS is somewhat frequent, it can incur high overhead and can cause a lot of interruptions to normal transmission/reception. One solution is to focus on the relatively long period SRS for SRS switching (e.g. 20 ms or more), especially if the switching gap is long. For shorter-term sounding, networks can rely on aperiodic SRS. In this case, long cycle SRS switching should have a relatively high priority. For example, the SRS switching priority of a 40 ms period may have a higher priority than other UL transmissions (except possibly those carrying Ack/Nack). This is common because the eNB can pre-schedul accordingly so that the Ack/Nack does not have to collide with long-period SRS, even if the Ack/Nack is designed as a lower priority one. It should be noted that it does not cause any problems. Another way is to allow a short period SRS for SRS switching, but with lower priority, which can reduce its interruption to normal transmission/reception. When a long period SRS collides with a short period SRS, the short one may be dropped.

A preferred resource for periodic SRS switching/transmission is the special subframe UpPTS. One example is a 20 ms period for subframe 1 (or subframe 6 for setting 0/1/2/6).

For deactivated carriers or carriers in DRX, periodic SRS is not transmitted according to current standards. Switching based on SRS carrier should follow the same principle, ie the UE will switch to its carrier for SRS transmission only if the TDD carrier without PUSCH is activated and in active time. This also helps reduce SRS switching overhead. No periodic SRS is sent when the UE is in DRX and/or deactivated. However, the aperiodic SRS may still be sent.

As mentioned above, it may also be possible to support only periodic SRS switching, since periodic SRS and aperiodic SRS can be configured and used very similar to each other.

General Assumptions and Considerations for Collision Handling Switching time is reported by the UE as part of the UE capabilities and is known by the UE and eNB. The report may indicate one or more of the following values: 0us, 30us, 100us, 200us, 300us, 500us, 900us. Not all values may be supported for SRS switching, especially for longer switching times. The report may be made for each CC pair, but the overhead is high. In general, the UE need only report the switching times of several categories. For example, in-band switching usually has the same switching time. In other examples, band-to-band switching may also have the same switching time. If the switch from band A to band B has a different time than the switch from band A to band C, then both times may be reported, or alternatively, the maximum of the two times is for simplicity. May be reported.

Collisions on some symbols, if they occur, are known to the UE and eNB before they occur.

The collision may cause the UE to be unable to use some resources (eg, subframes), but such resources are still available (for other UEs) to the eNB.

Multiple options can be considered and these may be combined.

Priority is defined to drop specific transmissions when collisions can occur.

This consideration is consistent with the RAN1 agreement and is awaiting a decision at the next meeting.

If the SRS switch affects the next subframe:
A/N has higher priority, SRS switch is dropped,
Aperiodic SRS has higher priority than other UCI/PUSCH,
Periodic SRS has a low priority.

FIG. 45 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, if the UE's SRS switch can collide with an A/N in subframe n+1, the switch in subframe n is dropped.

(E) PDCCH, scheduling request, RI/PTI/CRS may have higher priority than SRS. Aperiodic SRS may have higher priority than other CSI and short period P-SRS. When an aperiodic SRS collides with a (long or short) periodic SRS, the periodic one is dropped. If one periodic SRS collides with another periodic SRS, the one with the shorter period and/or the more recent SRS transmission is dropped.

Alternatively, the periodic SRS may be assigned a higher priority due to its predictability, so that the network can avoid certain collisions via the scheduling implementation scheme. For example, even a periodic SRS having 40 ms or more may be allowed to have a higher priority than Ack/Nack.

Moreover, different priorities can be defined for different subframe sets to avoid collisions and drops of SRS and other transmissions. For example, on one subframe set, SRS has lower priority than other UL transmissions, while on other subframe sets, SRS has higher priority than other UL transmissions. The set may relate to pre-configured UL transmissions (SRS or others), which allows these pre-configured UL transmissions to be better protected. For example, if the network wants to protect the periodic CSI feedback, the corresponding subframes (and possibly more) are SRSs with low priority subframes, the subframe patterns differ in time Since it may have granularity, it can signal to the UE that SRS may still be configured or triggered. Similarly, this can be used to protect SRS. The network can also schedule UL transmission according to subframe priority in the implementation.

Potential collisions can be avoided due to scheduling constraints and UE assumptions. For example, an SRS switch in subframe n may affect the next subframe n+1 (especially if the SRS transmit symbols are not fast enough in subframe n and the switch time is not short enough). Subframe n+1 may be scheduled for UL transmission (eg, ACK/NACK for the previous subframe). If the eNB has the information about the UE switch time and thus can know whether a potential collision may occur, this includes UL/DL transmission (including SRS transmission on the CC to which it is switching). ) That scheduling can be limited so that collisions do not actually occur. Correspondingly, the UE should be able to assume that SRS switching should be performed in subframe n and that SRS switching affects subframe n+1, and no transmission/reception by the UE is Envisioned via implementation method. If the SRS switch affects the next subframe:
The UE shall assume that the PUCCH (or PUSCH) is not scheduled for the next subframe,
The eNB should ensure this by not scheduling for the next subframe in DL or UL before several subframes.

Disadvantage: The entire next subframe may not be available to the UE (still available to other UEs by the eNB).

FIG. 46 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, if the SRS switching of the UE causes the start symbol of subframe n+1 to be lost for the UE, within subframe nk (related to n+1), the eNB is n Do not schedule UE in DL for +1 (with A/N in n+1) or UL.

SRS switching affects the A/N of the next subframe.

Suppose the SRS trigger is sent in DCI in subframe n. If DL grant is also present in subframe n, both PUSCH ACK/NACK and SRS need to be sent in subframe n+k, which can cause collisions. If there is a UL grant in subframe n, UL transmission shall also occur in subframe n+k and other collisions shall occur. Either new HARQ timing is introduced or reused for interruption due to measurement gap or SCell activation.

New and flexible SRS transmission timing is introduced, which delays SRS switching to the next acceptable SRS transmission opportunity without any other scheduled transmission. Alternatively, the SRS may be sent after n+k in the first subframe (eg, special subframe) with the SRS switch setting if there is no collision. The SRS switching setting may be preset in a cycle (for example, 5 ms, 10 ms, or 20 ms), and may include a special subframe. All SRS switching may be restricted to those subframes with SRS switching settings.

FIG. 47 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, the A/N may occur with conventional HARQ timing if it collides with the next subframe.

FIG. 48 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, when colliding with the next subframe, the A/N is avoided at the new HARQ timing with the bundled A/N.

Another option is an A/N alternative.

When SRS switching affects the A/N of the next subframe:
A/N is indicated by SRS transmission (eg, SRS switching is performed when it is ACK, or via SRS cyclic shift/sequence, or via comb, RB allocation, etc., eg Ack , Then Configuration 1 or Parameter Set 1 is used for SRS, otherwise Configuration 1 or Parameter Set 1 is used for SRS.Multiple Ack/Nack bits are also supported through SRS Parameter Set combinations. In this case, the network needs to set the parameter set and the association with Ack/Nack, or the parameter set for the aperiodic SRS may be reused here).

FIG. 49 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, if the SRS switch collides with a Nack, the SRS switch is dropped and the Nack is sent out.

FIG. 50 is a diagram of a carrier-based SRS switching scheme. As shown in the figure, in this example, when the SRS switch collides with the Ack, the SRS switch is sent and the Ack is sent.

Another option is to limit to conflict-free scenarios.

The UE can switch fast enough, eg, 0 us in-band, or
UpPTS is long enough, for example, with 4 or 6 OFDM symbols for SRS.

Example 1: UE switching time is 0 us → Switching in a special or UL subframe does not cause a collision with the next subframe.

Example 2: UE switching time is 30 us → All SRS symbols (except the last) in the special subframe can be used.

It should be noted that the UCI is not present in the special subframe and the PUCCH is punctured/shortened in the UL subframe with cell-specific SRS.

FIG. 51 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, the RF frequency alignment delay is not received by the UE.

FIG. 52 is a diagram of a carrier-based SRS switching scheme. As shown, in this example, a relatively short RF frequency alignment delay is experienced by the UE.

If the switching subframe or the next subframe carries the PUSCH, the PUSCH can be punctured to the DMRS of the PUSCH. In other words, the DMRS should not be punctured and the priority/drop rule applies if the SRS switch overlaps with the DMRS symbol. The punctured PUSCH may be transmitted with higher power, lower MCS level or modified beta value, which may improve reliability.

The other option is to change the TA.

Restrict to special subframe SRS switching, the network specifies a longer TA for the CC to switch to (if the CC is in a different TAG).

Via RAR and/or TA adjustment.

FIG. 53 is a diagram of a carrier-based SRS switching scheme. The SRS is sent on the last symbol of subframe n on CC2, so if normal TA on CC2 is applied, the RF frequency tuning for the revertive operation is the start of subframe n+1. It overlaps with the symbol. As shown, in this example, there is a collision with subframe n+1 with a normal TA for CC2.

FIG. 54 is a diagram of a carrier-based SRS switching scheme. SRS is still transmitted on the last symbol of subframe n on CC2, but a larger TA is indicated, the UE performs the switch to CC2 and the SRS transmission on CC2 earlier, so The UE may switch back to CC1 earlier so that it does not overlap with subframe n+1. As shown, in this example, there is no collision with subframe n+1 with a larger TA for CC2.

An example is embedding the A/N (or UCI) in the PUSCH. One problem with this is that there may not be any PUSCH scheduled for that subframe. To resolve this, the eNB may indicate to the UE that PUSCH should be used instead of PUCCH for the upcoming conflicting subframes. The PUSCH resource allocation may be sent in DCI. Alternatively, the PUSCH may be semi-persistently scheduled, ie configured as SPS. The eNB may set the SPS period to be the same as the SRS switching period so that the subframes affected by the SRS switchback operation can use the punctured PUSCH for UCI.

SRS power control should also be incorporated into CC without PUSCH. To support closed-loop power control, the network needs to configure a new TPC-SRS-RNTI for CC without PUSCH in SRS transmission. The TPC command cannot be sent with DL permission and is carried with UL permission in DCI. However, these PUSCH-less CCs do not have UL approval for them. Therefore, inter-carrier indication of TPC command for CC without PUSCH is needed. The cell ID associated with the TPC command needs to be indicated in the UL license with format 0/4. Alternatively, the DL grant can be modified for SRS TPC with inter-carrier indication or same-carrier indication. Group DCI 3/3A may be used as an alternative, but TPC-SRS-RNTI needs to be used and inter-carrier or same-carrier indication may be allowed. This needs to be specified because the reference power Po_PUSCH is not available for CCs without PUSCH. This may be replaced by a new value Po_SRS for CC without PUSCH. Alternatively, a different CC Po (with PUSCH) may be used for this PUSCH-less CC. In either case, the network should be specified in the RRC settings. Below is the configuration of one embodiment of SRS and PRACH on CC without PUSCH, updated from TS 36.331.

-RadioResourceConfigCommon
IE RadioResourceConfigCommon SIB and IE RadioResourceConfigCommon are used to specify common radio resource settings in system information and mobility control information, eg, random access parameters and static physical layer parameters, respectively. Table 3 provides the settings for the radio resource settings common information element. Tables 4 and 5 provide a description for various SRS parameters.

SRS switch source CC and switch destination CC
The set of agreements for SRS switching between LTE Component Carriers (CCs) reached in RAN1 #86 includes:
In addition to all existing parameter settings,
If the UE supports multiple switching source CCs,
Option 1: Defined rules Option 2: Selected by RRC setting.

The details of the examples of the SRS switching source CC and the switching destination CC will be described below.

CC to switch from
For SRS switching, it is necessary to specify the switching source CC. The switching source CC is the CC whose UL transmission is suspended when the SRS is transmitted on the CC without the switching destination PUSCH. The reason to suspend UL transmission on the switching source CC is to avoid exceeding the UE's UL CA capability.

To analyze how to specify the CC to switch from, the following cases are considered.

Case 1: Case of Only One Allowed Candidate CC Having PUSCH In this case, for a CC having no PUSCH of the switching destination, there is only one candidate CC having the PUSCH as the CC of the switching source. In that case, the switching source CC must be only the candidate CC. The switching source CC can be specified in the standard. There is no need to set the RRC of the switching source CC.

There are some scenarios where there is only one candidate CC with PUSCH allowed as the source CC for the target CC:

Case 1-1: UE does not support UL CA.

For this UE it supports only one CC with PUSCH, namely PCell. The switching source CC must be PCell.

Case 1-2: The UE supports UL CA, but the RF architecture of the UE's transmitter allows only one candidate source CC for the destination CC.

As an example, assume that the UE supports two bands and two CCs in each band (CC1/CC2 in band 1 and CC3/CC4 in band 2). CC1 is a PCell having PUCCH/PUSCH, and CC3 is a SCell having PUSCH. The RF architecture of the UE may use a dedicated RF for each band rather than another band. In that case, switching from CC3 to CC2 for SRS transmission on CC2 is infeasible, and switching from CC1 to CC4 for SRS transmission on CC4 is also infeasible. Therefore, CC1 is the only switching source candidate for CC2, and CC3 is the only switching source candidate for CC4. Of course, such restrictions have to be reported by the UE to the network, so that both the network and the UE are aware before setting up the SRS switch.

Although this example may seem desirable to always use an SCell with PUSCH as the switching CC for a UE supporting UE CA, this may not always be feasible. It also indicates that there is. UL-CA capable UEs may still have to use PCell as the CC to switch from for some PUSCH-less CCs, despite the fact that they have SCells that support PUSCH ..

Case 2: Case of Only One Preferred Candidate CC with PUSCH In this case, for a CC without a PUSCH to switch to, there are multiple allowed candidate CCs with PUSCH to be the CC to switch from, but As the original CC, there is only one preferred candidate CC with PUSCH. There are two scenarios:

Case 2-1: Only preferable candidates can be determined in advance.

In this scenario, only preferred candidate CCs are UE capabilities (which are reported to the network) and CC settings (eg which CCs are PCells, which CCs support PUSCH, which CCs to switch to) It is necessary to become CC, etc.) and can be determined in advance. Candidate CCs can be preconfigured via RRC signaling, or specified in the standard and determined by the UE/eNB without signaling.

There are several different cases:

Case 2-1-1: Only preferred candidates are determined by RF requirements and efficient requirements in existing standards.

The UE may support UL CA, and the UE's transmitter RF architecture allows multiple candidate source CCs for the target CC, but the RF requirements in existing standards are Limit the original CC to be effectively one for the new CC. An example of RF requirements in existing standards is the continuous requirement for in-band UL CA. To date, the RF requirements of RAN4 only allow continuous UL CA. This limits the candidates to switch from. For example, assume there are consecutive CC1/CC2/CC3 in the band and CC2 is between CC1 and CC3. It is assumed that the UE supports all three CCs for PDSCH aggregation and CC1/CC2 for PUSCH aggregation. If the UE needs to switch to CC3 for SRS transmission, the UL on CC1 shall be suspended to avoid violating the continuity requirement. Therefore, it may appear that either CC1 or CC2 can switch to CC3, but CC2 is not a preferred candidate, and in fact, only CC1 can be the switching CC ( If CC2 is selected as the switching source CC for CC3, neither CC1 nor CC2 can be sent when sending an SRS on CC3, which is a poor design with low efficiency).

Case 2-1-2: One allowed candidate is PCell and the other allowed candidate is SCell.

If the PCell is one of the two allowed candidates, it should be protected as much as possible and the SCell should be the CC to switch to (but the continuity requirement in the above RF is If PCell decides it is not preferred, SCell should be selected as CC to switch from).

Case 2-1-3: The accepted candidate is SCell, but only one is separated from PCell over the others. The binding may be due to the shared RF by the PCell and the candidate SCell.

It is desirable to select an SCell whose switching source operation does not affect PCell. For example, when the SCell having the PUSCH is in the same band as the PCell (or shares the RF with the PCell), another SCell having the PUSCH is preferably selected as the switching source CC. Otherwise, the PCell may be interrupted during RF frequency tuning with SRS switching. This can be done either via rules or RRC settings and the result is the same.

Case 2-1-4: Only one preferred candidate is selected by other criteria.

If all switching operations of the candidate SCell affect the PCell, or if any switching operations of the candidate SCell do not affect the PCell, the operation (for example, UL transmission) is likely to collide with the SRS switching. It may be desirable to select a small SCell.

Furthermore, it may be desirable to select an SCell whose operation (eg UL transmission) matches another SRS switching operation by the UE.

Further, it may be desirable to select a SCell whose switching source operation is faster from other candidates.

The above procedure may result in a unique selection of CC to switch from. In this case, the unique selection can be determined by the UE/eNB if they follow the same selection rule, or alternatively, the eNB decides and configures for the UE via RRC signaling, which is a rule-based selection. Should have the same result as

Case 2-2: Only preferred candidates can be determined during execution.

Case 2-2-1: When all the switching source operations of the candidate SCell affect the PCell, or when the switching source operations of any candidate SCell do not affect the PCell, the operation (for example, UL transmission) is performed. It may be desirable to select SCells that do not conflict with SRS switching. One such example is an idle SCell or a deactivated SCell. That is, this allows the network/UE to utilize the degrees of freedom of the carrier area to avoid collisions. However, this cannot be pre-configured and must rely on the eNB and UE to make decisions during execution.

Case 2-2-2: Furthermore, it may be desirable to select an SCell whose operation (eg UL transmission) matches another SRS switch by the UE.

Case 2-2-3: Furthermore, it may be desirable for the switching source operation to select a faster SCell from other candidates.

Case 3: Case of Multiple Candidate CCs with PUSCH When the above rules (where applicable) still result in multiple candidates for switching from, the following may be considered:

Case 3-1: The switching source CC may be designated as any one of the candidates, and the RRC setting of the switching source CC can be used to avoid ambiguity. This may have the advantage that the network controls the switching CC in the cell coverage area.

Case 3-2: The switching source CC may be designated as the SCell having the highest CC index.

Case 3-3: The switching source CC may be any of the candidate SCells. The switching source CC options have no difference for UE transmission/reception and can be transparent to the eNB.

In addition to suspending UL transmission on the switching source CC while the switching destination CC is transmitting SRS, UL transmission on the switching source CC (and in some cases DL reception) It may be interrupted (before and after SRS transmission on the CC to which it is switching) during the RF tuning time. When a collision occurs due to an interruption, collision processing can be applied.

In case of dual connectivity, inter-group switching is not supported due to lack of fast communication/coordination between MCG and SCG. Therefore, the above discussion was cell group specific. When the above discussion applies to SCG, PCell indicates a PSCell within a group. Therefore, the switching source CC and the switching destination CC are in the same cell group.

The switching source CC may be deactivated. This does not affect the CC to be used as the switching source CC. If a rule-based approach is used, it may be preferable to select a deactivated SCell as the CC to switch from. Similarly, if a rule-based approach is used, it may be preferable to select SCell in DRX as CC to switch from.

Findings Based on the arguments detailed above, the following can be observed here:

The switching source CC for switching may be determined in advance or may be determined during execution.

Approaches based on RRC settings yield predetermined results.

If the rules are based solely on static settings (UE capabilities and CC settings), the rule-based approach yields predetermined results.

If the rules depend on the results of dynamic scheduling, the rule-based approach requires the UE/eNB to determine the CC to switch from during execution.

In most cases, the rule-based approach using only static configuration and the RRC configuration-based approach yield the same result, and the rule is easy to write and implement.

In some cases, the rule-based approach using only static configuration may provide some flexibility over the RRC configuration-based approach, with somewhat higher complexity in eNB and UE.

In some other cases, a rule-based approach based on the results of dynamic scheduling may provide greater flexibility and reduce collisions at the expense of increased complexity in eNBs and UEs.

In the few cases, switching from any of the set of CCs can be transparent to the network.

Therefore, the embodiment adopts the RRC setting of the switching source CC. The switching source CC's RRC configuration may take into account UE capabilities and RF requirements, and may also take into account the reduced negative impact on other operations.

In the embodiment, the switching source CC is set via RRC signaling.

It is necessary for the UE to report sufficient information for SRS switching configuration, eg switching time for inter-band RF frequency tuning and in-band RF frequency tuning. In some cases, the inter-band frequency alignment time depends on the particular band pair, in which case the UE needs to report different frequency alignment time for different band pairs. In some cases, the inter-band frequency alignment time depends on the particular CC pair, in which case the UE needs to report different frequency alignment time for different band pairs. In some cases, the in-band frequency alignment time depends on the particular CC pair, in which case the UE needs to report different frequency alignment time for different CC pairs. In some cases, inter-band and in-band frequency tuning times depend on the activity of specific CC pairs and CC pairs, or bands with CC pairs, in which case for different band pairs, the UE can It is necessary to report the maximum frequency alignment time for CC pairs under activity. In some cases, the UE may select a CC pair to report to the eNB, which may further select from those reported for SRS switching.

Switching destination CC and setting/instruction
For SRS switching, the CC to switch to needs to be specified.

For periodic SRS switching, the CC to switch to has to be configured via RRC signaling.

For the aperiodic SRS switching, the CC to switch to may be configured via RRC signaling, or jointly determined via RRC configuration and A-SRS trigger.

The A-SRS trigger contains a 3-bit CIF. In that case, the CC to switch to is a CC related to CIF. It may be used for A-SRS trigger based on DL DCI and group DCI, CIF must be enabled and configured, ie inter-carrier scheduling/indication is configured.

The A-SRS trigger does not include the CIF, but the bits sent in the A-SRS trigger are associated with the CC via the RRC setting. In that case, the related CC is the CC to be switched to. For example, for a CC where the UE is monitoring an A-SRS trigger, parameter set 1 is configured for SRS configuration on CC1, parameter set 2 is configured for SRS transmission on CC2, and parameter set 3 is set for SRS transmission on CC3, and so on. It should be noted that multiple parameter sets can be configured for SRS transmission on the same CC (SRS transmission settings may be different for different parameter sets).
It may be used for A-SRS trigger based on DL DCI and group DCI, which does not require inter-carrier scheduling to be configured.

The A-SRS trigger does not include the CIF and the bits sent in the A-SRS trigger are not associated with the CC via the RRC setting. In that case, the CC that received the A-SRS trigger is the CC to switch to. It may be used for A-SRS trigger based on DL DCI and group DCI, which does not require inter-carrier scheduling to be configured.

The above three options can be combined and all can be supported. If the UE is configured with inter-carrier scheduling for some carriers, it is reasonable to reuse CIF for SRS switching for these carriers, otherwise A-SRS trigger parameter set or The same carrier indication can be used to specify the CC to switch to.

In the embodiment, the CC to which the P-SRS is switched is specified by the RRC setting signaling.

In an embodiment, the CC to which the A-SRS is switched has received the CIF (if configured), the A-SRS trigger bit and the associated parameter set set by the RRC, RRC configuration signaling only or the A-SRS trigger. Specified by CC.

Switching for RACH on CC without PUSCH
For RACH on CC without PUSCH, the switching source CC and the switching destination CC also need to be specified. The CC to switch to is the CC indicated by the PDCCH order for RACH (ie, if the CIF is present, the CC associated with the CIF value should send the RACH; otherwise, the PDCCH order). Should receive a RACH), which is the same operation as the current RACH. There are several alternatives for the CC to switch from:

The switching source CC for the RACH PDCCH command is preset by RRC signaling. In this case, for the same CC, the associated switch source CC for RACH and the switch source CC for SRS may be different.

The switching source CC for RACH on the CC is specified as the switching source CC for SRS switching. This is a simple solution, but it cannot be used for CCs whose switching source is not predetermined. If the CC option from which the SRS switch is determined at run time is not supported, this option should be supported for simplicity. Alternatively, the rules used to determine the switching source CC for SRS switching utilize deactivated CC or CC in DRX, for example to avoid/reduce interruptions to PCell or PSCell. It can also be applied here for switching for RACH.

In the embodiment, the CC to switch to for RACH on a CC without PUSCH is the CC indicated by the PDCCH command.

In the example, the switching source CC for RACH on the CC without PUSCH is the same as the switching source CC for the associated SRS switching.

DCI design for SRS switching
The set of agreements on SRS switching between LTE CCs reached in RAN1 #86 includes:
Downlink selection options from the TPC command:
Option 1: According to UL authorization DCI0/4 (with inter-carrier indication)
Option 2: By DL DCI (with inter-carrier indication)
Option 3: By Group DCI Adopt Option 3 and apply only to SRS-only CC without PUSCH Joint group DCI for trigger and TPC
FFS: Introduce RNTI for number of bits per UE and field state meaning group
For A-SRS, the triggers are carried in:
DL scheduling DCI and group DCI
Group DCI is used for SRS only CC without PUSCH.

Details of an embodiment of downlink control information (DCI) design are described below.

Group DCI at joints for TPC commands and A-SRS triggers
A new group DCI format is needed to support the TPC command and joint indication of A-SRS. The existing group DCI format 3/3A for TPC commands can be considered as a basis for new designs, incorporating A-SRS triggers. Several aspects are discussed below.

Search Space Group for DCI The DCI needs to be sent in the search space common to the group of UEs instead of the UE specific search space. One option is to use a common search space in PCell, which then requires significant signaling overhead for inter-carrier indication and can cause more collisions in the common search space. The other option is to have the lowest index CCE (0-3 for aggregation level 4 and 0 for aggregation level 8 as well as when the UE monitors DCI format 1C on each LAA SCell introduced in Rel-13. ~ 7) to use the search space in each CC without PUSCH. If more search space is needed (eg to support two DCIs for two groups of UEs in one subframe), CCE4-7 are included for aggregation level 4. May be. Yet another option is to use a search space within each CC where the UE monitors the PDCCH with the lowest index CCE. The PDCCH on these CCs may include CIFs for inter-carrier scheduling on other CCs and the same inter-carrier indication relationship is used to indicate CCs for TPC commands and A-SRS triggers. It should be noted that this is possible.

The UE needs to monitor the search space with the lowest CCE index associated with each SRS switching CC, on a set of PCell and SCell, or on all serving cells or UEs on all serving cells that monitor the PDCCH. Observed here.

Payload size for DCI
To help reduce the number of blind detections by the UE, the group DCI (including possibly zero padding) payload size is preferably equal to the size of the DCI that the UE is already monitoring. In general, the UE monitors the DCI format 0/1A associated with each CC, so the payload size of the group DCI is preferably equal to that of DCI format 0/1A on the same CC. It should be noted that DCI format 3/3A also has the same size as DCI format 0/1A.

It is observed here that the group DCI payload size (with padding) should be the same as DCI format 0/1A.

RNTI for DCI
A common RNTI is required for a group of UEs within the carrier. Each UE in the group is set by the group RNTI. The range of RNTI values can be the same as for PUSCH/PUCCH TPCs. If the number of UEs in the carrier is large, it may be necessary to configure more than one group RNTI on the carrier, so that different UE groups are associated with different group RNTIs. One RNTI may be set for all SRS switching CCs of the UE, or alternatively, each SRS switching CC is set with a CC-specific RNTI. If the new DCI format supports TPC only content and TPC+ trigger content, these may also be distinguished by different group RNTIs.

It is observed here that the group RNTI needs to be set for the group DCI.

Instruction of UE and CC in DCI
One option for DCI design is for the DCI to indicate the UE only, not the CC to which the UE switches. This corresponds to the case where it is not an inter-carrier instruction. In this case, the UE needs to monitor the group DCI on each CC with SRS switching, but the CIF does not have to be in the DCI and the overall overhead may be reduced. The indication of the UE may be similar to that in DCI format 3/3A, ie each UE associated with the group is configured with an index of its position in the PDCCH.

Another option is to indicate both the UE and the CC associated with the TPC command and A-SRS trigger. In other words, inter-carrier instructions are used. It should be noted that inter-carrier indication from PCell only is not desirable as it may require up to 5 bits (or equivalent) to specify the CC for the UE. However, the current inter-carrier indication mechanism of CIF up to 3 bits may be adopted. Further, similarly to the DCI format 3/3A, each UE associated with the group is also set by the position index in the PDCCH.

It is possible that the group DCI indicates the UE via the index of the position within the PDCCH and indicates the CC of the UE via the 0-bit CIF (same carrier indication) or the 3-bit CIF (inter-carrier indication). To be observed.

TPC commands in DCI
All DCI formats with TPC commands use a 2-bit field in the TPC command for PUSCH/PUCCH, except that only 1 bit is used in 3A. Therefore, if it is reasonable to support a 2-bit field in the new group DCI for SRS TPC commands and a compact format is needed, a 1-bit field may also be considered.

It is observed here that the group DCI supports a 2-bit field or a 1-bit field per TPC command.

A-SRS trigger in DCI
In DCI format 0/1A/2B/2C/2D/6-0A/6-1A, 1-bit trigger is used for A-SRS, while in DCI format 4, 2-bit trigger is used. Both may be supported for the new group DCI. For a 1-bit trigger, one A-SRS parameter set can be supported, while for a 2-bit trigger, three A-SRS parameter sets can be supported. If more A-SRS parameter sets are needed, then at most one more bit (ie, at most 3 bit trigger) may be considered. On the other hand, for each DL CC (including each FDD CC if aggregated), there can be up to 3 configured parameter sets, which in total is sufficiently large to be available for aperiodic SRS. Can result in a parameter set. In other words, RAN1 may consider increasing the number of SRS required bits or supporting carrier-specific SRS parameter set settings.

It is observed here that the group DCI supports at least 1-bit and 2-bit triggers for A-SRS.

The time offset between the trigger and the associated SRS transmission is already specified in existing standards and can be reused for SRS switching. However, if there is a need to change the time offset for the SRS switch to help avoid collisions with other transmissions, the time offset can be included in the trigger as well as the eLAA SRS trigger. Good. The time offset within the group DCI may be common to all SRS requests within the DCI.

For group DCI for TPC commands and A-SRS, embodiments provide support for one or more of the following:
Search space with the lowest index CCE on all serving cells (same carrier indication) or on all serving cells where UE monitors PDCCH (inter-carrier indication)
Same payload size as DCI format 0/1A (with padding)
Group RNTI
0-bit CIF (same carrier indication) or 3-bit CIF (inter-carrier indication)
2-bit TPC command and compact format 1-bit TPC command At least 1-bit and 2-bit trigger Optional time offset indication.

The above discussion may result in numerous combinations of DCI format content. For simplicity, downward selection of DCI format content should be considered.

First, there are cases where A-SRS may not be configured or triggered, but TPC commands may be needed for P-SRS. Therefore, it makes sense to have a DCI format that has only TPC. It is effectively DCI format 3/3A, but on CC that supports P-SRS or SRS transmissions. The other fields need not be included in the DCI format. RNTI may be referred to as SRS-TPC-RNTI. It should be noted that the length of DCI format 3/3A is the same as DCI format 0/1A.

Secondly, when A-SRS is configured, the group DCI needs to include SRS requests for A-SRS and their associated TPC commands. There are at least three combinations: 1) 0 or 3 bit CIF, 2) 1 or 2 bit TPC, and 3) 1 or 2 bit trigger. To further simplify, the UE does not have to consider the TPC-only DCI format on each CC with SRS, so the UE does not consider the inter-carrier indication, and the A-SRS for the TPC+triggered DCI format. It should be noted that it is reasonable to monitor each CC with In that case, a 1- or 2-bit TPC and a 1- or 2-bit trigger may be supported, which results in four combinations, which may be distinguished by a 2-bit flag in the DCI or RNTI. Alternatively, a further downward selection can be considered.

Examples for group DCI focus on the following downward selections:
DCI with TPC only on each CC with P-SRS (similar to 3/3A)
TPC+ Trigger DCI on each CC with A-SRS with 1 or 2 bit TPC and 1 or 2 bit trigger
DCI with TPC only
Reuse DCI format 3/3A
UE has configured group RNTI to monitor this format on each CC with P-SRS in search space with lowest index CCE
TPC+ trigger DCI
Has 1 or 2 bit TPC and 1 or 2 bit trigger
Same payload size as DCI format 0/1A (with padding)
The UE has a configured group RNTI that monitors this format on each CC that has an A-SRS in the search space with the lowest CCE, and possibly has a time offset indication.

Other variations can be considered. For example, to notify the UE whether DCI is for TPC only, a 1-bit flag is included in DCI, or whether the DCI is for trigger only UE In order to notify the UE, whether the 1-bit flag is included in the DCI, or DCI is TPC only, TPC + trigger, to notify the UE whether or not it is for trigger only, a 2-bit flag, Included in DCI. Furthermore, the flag can be used to inform the UE of the length or presence of some fields, eg 1 or 2 bit TPC, 1 or 2 bit trigger, time offset present, CIF present, etc. The flag may be jointly encoded. Alternatively, the flag may not be present and the DCI format content difference is signaled via the group RNTI. In other words, for UEs using different formats, these are configured in different groups, each group associated with a dedicated RNTI.

DL DCI for A-SRS trigger
Currently, aperiodic SRS is configured via RRC signaling and dynamically triggered via DCI format 0/1A/2B/2C/2D/4 for TDD and 0/1A/4 for FDD .. Of these, DCI format 1A/2B/2C/2D is for DL. These DCI formats may be extended to support A-SRS switching. It does not seem necessary to support other DL DCI formats for A-SRS switching. If aperiodic SRS is not configured on the serving cell, the SRS Request field may still be present and current standards do not specify how the UE should utilize it. This field is now useful for triggering A-SRS on the relevant CC. The associated CC may be the CC that received the DCI (if CIF is not set) or a different CC (if CIF is set). No changes in the standard are required to support this behavior, except that RRC signaling is needed to configure A-SRS on the relevant CC.

Similar to "A-SRS Trigger in DCI" above, the number of bits and time offset are as follows. The DL DCI format has a 1-bit trigger. It is probably necessary to increase the trigger by at least 2 bits. This will change the DCI payload size and the network should set to the UE whether a new payload is used. In addition, a time offset may be included so that the triggered SRS switch and transmission can be at a different time than the ACK/NACK associated with DL DCI.

For DL DCI 1A/2B/2C/2D for A-SRS, the embodiments provide 2-bit triggering, and optionally support for time offset indication.

Other considerations for SRS switching
The set of agreements on SRS switching between LTE CCs reached in RAN1 #86 includes:
R14 SRS switch supports RF tuning times no longer than Xus Option 1: X=200
Option 2: X=300
Option 3: X=500
Option 4: X=900

Furthermore, in the discussion of RAN4 it was raised whether to support SRS switching to deactivated CC. Details of examples of maximum switching time support for Rel-14 and SRS switching to deactivated CC are described below.

The maximum RF switching time that should be supported for Rel-14 SRS switching The following RF switching times have been agreed by RAN4:
[RAN4]: Given that the RF switching time may have some dependency on the CA scenario and the UE implementation, RAN4 has agreed that the RF switching time can be specified as the following values:
0us
30us
100us
200us
300us
500us
900us

In the RAN1 design, it is useful to make a decision about the maximum switching time so that RAN1 can provide efficient support for UEs with switching times no longer than the maximum. In order to choose the maximum value, it is desirable to consider a switching time that may have no or little negative effect on other transmissions and receptions. If the switch time always negatively impacts other transmissions and receptions for any setting, RAN1 can consider how to effectively support such switch time in later releases. ..

It can be seen that for switching times of 500 us and above, there is always a negative impact on other transmissions and receptions for either setting. To recognize this, note that 500us becomes 8 OFDM symbols. The next subframe is affected regardless of whether the SRS is transmitted within the currently supported SRS symbol positions. Therefore, in the embodiment, X should be strictly less than 500 us.

On the other hand, if the switching time is less than 300 us, there is at least one setting in which other transmissions or receptions are not affected at all, even when the maximum timing advance difference (32.47 us) is taken into account. To recognize this, note that 300us plus 32.47us results in at most 5 OFDM symbols. With TDD special subframe setting 0 (3 OFDM symbols for DwPTS) and 6 OFDM symbols for UpPTS, SRS transmission can be performed on the first symbol of UpPTS and DwPTS of the current subframe is also None of the symbols in the subframe are affected by the SRS switch. If the switching time is shorter, it does not affect other operations, more settings can support SRS switching, and more SRS transmission positions are acceptable. Therefore, in the example, X is selected as 300 us.

In an embodiment, the R14 SRS switch supports an RF tuning time no longer than 300 us.

It should be noted that for deactivated carriers, SRS is not transmitted according to current standards for deactivated carriers. SRS switching between LTE component carriers should also follow the same principle, ie the UE will not switch to a PUDD-less TDD carrier for SRS transmission if it is deactivated. This also helps reduce SRS switching overhead. An LS from RAN1 to RAN4/2 can be considered to clarify this issue.

The following excerpts from TS36.321 are included for information:
5.13 SCell activation/deactivation
The MAC entity is for each TTI and for each configured SCell:
-When SCell is deactivated:
-Do not send SRS on SCell.

In the example, there is no switch to the deactivated CC due to the SRS switch.

Introduced Power Headroom Report for SRS switching
The set of agreements on SRS switching between LTE CCs for power headroom reporting for power control mechanisms reached in RAN1 #86 includes:
Support for two types of PHR similar to Rel-13

Details are FFS.
Details of an example for two types of power headroom reporting for SRS on TDD CC without PUSCH are described below.

ここで、P_CMAX,c(i)はサービングセルcについてサブフレームi内でTS36.101において規定された設定されたUE送信電力であり、P_{O_SRS,c}(j)及びα_SRS,c(j)はサービングセルcについてサブフレームi内でのSRS電力制御のために規定されたパラメータであり、P-SRSについてj=0であり、A-SRSについてj=1であり、M_SRS,cはリソースブロック数で表現されたサービングセルcについてサブフレームi内でのSRS送信の帯域幅であり、f_SRS,c(i)はサービングセルcについての現在のSRS電力制御調整状態である。 A Study of PH for SRS on TDD CC without PUSCH
The power control formula for SRS on TDD CC without PUSCH, if the UE transmits SRS in subframe i for serving cell c, the transmit power can be calculated based on the following formula:

Here, P _CMAX,c (i) is the UE transmission power set in TS36.101 within subframe i for serving cell c, and P _{O_SRS,c} (j) and α _SRS,c (j) Is a parameter specified for SRS power control in subframe i for serving cell c, j=0 for P-SRS, j=1 for A-SRS, M _SRS,c is a resource block Is the bandwidth of SRS transmission in subframe i for serving cell c expressed as a number, and f _SRS,c (i) is the current SRS power control adjustment state for serving cell c.

ここで、P_CMAX,c(i)はサービングセルcについてサブフレームi内でTS36.101において規定された設定されたUE送信電力であり、P_{O_SRS,c}(j)及びα_SRS,c(j)はサービングセルcについてサブフレームi内でのSRS電力制御のために規定されたパラメータであり、P-SRSについてj=0であり、A-SRSについてj=1であり、M_SRS,cはリソースブロック数で表現されたサービングセルcについてサブフレームi内でのSRS送信の帯域幅であり、f_SRS,c(i)はサービングセルcについての現在のSRS電力制御調整状態である。 The remaining issue is PHR for SRS on TDD CC without PUSCH. Based on the power control equation, if the UE sends SRS in subframe i for serving cell c, PH can be calculated based on the following equation:

Here, P _CMAX,c (i) is the UE transmission power set in TS36.101 within subframe i for serving cell c, and P _{O_SRS,c} (j) and α _SRS,c (j) Is a parameter specified for SRS power control in subframe i for serving cell c, j=0 for P-SRS, j=1 for A-SRS, M _SRS,c is a resource block Is the bandwidth of SRS transmission in subframe i for serving cell c expressed as a number, and f _SRS,c (i) is the current SRS power control adjustment state for serving cell c.

ここで、

はMPR=0dB、A-MPR=0dB、P-MPR=0dB及びΔT_C=0dBと仮定して計算され、MPR、A-MPR、P-MPR及びΔT_CはTS36.101に規定されている。 If the UE does not send SRS in subframe i for serving cell c, PH can be calculated based on the following equation:

here,

Is calculated assuming MPR=0 dB, A-MPR=0 dB, P-MPR=0 dB and ΔT _C =0 dB, and MPR, A-MPR, P-MPR and ΔT _C are specified in TS36.101.

In the example, the two types of PH _SRS,c (i) are calculated based on the agreed SRS power control equations, and various alternatives are given for how the SRS-only PHR is triggered and reported. Exists.

Collision handling for SRS switching Collision analysis There are collisions caused by different reasons, and these may take different forms. To effectively deal with collisions, the following collision analysis is provided.

Type 1: Collision caused by UE capability limitation or requirement violation
Collisions may occur if the operations configured/scheduled for the UE exceed UE capabilities. Furthermore, a collision may occur if the operation configured/scheduled for the UE violates requirements/rules such as bandwidth combination requirements.

For example, UE that can be transmitted at one time in UL on one CC, while simultaneously transmitting on the switching source CC, transmitting the SRS on the switching destination CC exceeds the UL capability of the UE, therefore, This is a collision. In this case, only one transmission is acceptable at a time. See [1] for a discussion of the target and source CCs for SRS switching.

In another example, for a UE that supports two UL CC CAs, if the UE can support only one band at a time, or if RF requirements prohibit simultaneous transmissions on bands A and B, then the band The transmission of SRS on CC1 in A and other signals on CC2 in band B can result in collisions.

In yet another example, performing two transmissions on overlapping resources so that instructing the UE to transmit A-SRS on the same symbol as the configured P-SRS causes a collision. Configuring/scheduling the UE to do so also causes a collision.

Type 2: Collisions caused by RF tuning Collisions can occur during RF tuning.

For example, while switching from CC1 to CC2, RF frequency tuning may cause all CCs in the same band as CC1 to be unable to transmit, which does not allow all CCs to transmit in the same band as CC2. It can also cause things.

In another example, if the SRS transmission on CC without PUSCH is performed within the last OFDM symbol of a subframe, and if the UE's RF frequency alignment time is not 0, then the next subframe (UL or DL) Will be affected.

Type 1 collisions may occur on the symbols for SRS transmissions by the CC to switch to. On the other hand, type 2 collisions may occur during the RF frequency tuning time of the SRS switch, rather than on the symbol for the SRS transmission by the target CC. Both UL and DL may be affected during a collision. Similarly, RACH transmission on CC without PUSCH can also cause both kinds of collisions. The collision handling mechanism should be applied to all signals on all OFDM symbols of all affected CCs during collision.

The collision handling mechanism should be applied to all signals on all OFDM symbols of all affected CCs during collision.

Collision handling for SRS on TDD CC without PUSCH In case of collision, how to determine which transmissions (or receptions) are retained/dropped, and extensions to avoid collisions Should be specified.

Potential solutions may be:
Option 1: Define priority/drop rules.
Option 2: Allow punctured signals.
Option 3: Change A-SRS timing or HARQ timing.

In Option 1, assuming specific configured SRS transmission, when there is a collision with PUSCH/PUCCH/PRACH/ etc. in another UL carrier, periodic/aperiodic SRS type and channel/UCI type and PCell Factors including /SCell type may be considered when determining drop rules and prioritized transmissions.

SRS switching can have higher priority than regular data transmission (PUSCH/PDSCH).

DL control channel, (E)PDCCH should have higher priority than SRS switching.

Signals carrying RRC configuration information, MAC control information and associated feedback should have higher priority than SRS switching.

As a general guideline, ACK/NACK, signals carrying SR, signals involved in the RACH procedure should have a higher priority than SRS switching. However, if the negative impact of SRS switching on ACK/NACK can be limited (eg, via the RAN4 requirement of lost ACK/NACK for CC which should not be greater than 0.5% by SRS switching), then A-SRS And long-period P-SRS may have higher priority than ACK/NACK.

SRS switching should have a higher priority than CSI feedback on the TDD CC, as SRS provides a better means of obtaining CSI. However, long term CSI feedback carrying RI/PTI/CRI for FDD CC should have higher priority than SRS switching.

The priority/drop rules should be applied after collision avoidance via puncturing the signal is applied. In other words, if puncturing the signal can resolve the conflict, priority/drop roll is not applicable. Otherwise, the priority/drop rules apply.

Example: Consider the following priority/drop rules:
(E)PDCCH RI/PTI/CRI for FDD, RRC/MAC signaling, SR, RACH, [ACK/NACK]>A-SRS>Long cycle SRS>[Other ACK/NACK]>Short cycle SRS >Other CSI>Normal PUSCH/PDSCH.

Option 2 can incorporate several forms of punctured PUCCH/PUSCH/PDSCH formats to handle collisions of SRS transmissions on different carriers. The PUCCH/PUSCH/PDSCH symbols that overlap with the SRS switch may be punctured, so that both the punctured signal and the SRS switch may be maintained.

This is an existing partial PDSCH/PUSCH such as LAA/eLAA, such as partial ending subframe, subframe with only one slot, PUSCH with no first or last symbols, etc. You may consider reusing as much as possible. The number of symbols to be transmitted/received does not need to be indicated to the UE, since both the eNB and the UE recognize how many symbols overlap with the SRS switching.

Punctured PDSCH can be considered.

Punctured PUSCH can be considered. However, the PUSCH DMRS symbols should not be punctured and the priority/drop rules should be applied if the DMRS is affected. Furthermore, if ACK/NACK is embedded in PUSCH, ACK/NACK symbols should not be punctured, and if ACK/NACK is affected, priority/drop rules should be applied.

Punctured PUCCH can be considered. However, PUCCH DMRS symbols should not be punctured, and priority/drop rules should be applied if DMRS is affected. Puncturing may or may not result in non-orthogonality between multiplexed UEs depending on the PUCCH format and the means of multiplexing. If the PUCCH format specified in TS36.213 uses orthogonal cover codes in the time domain on PUCCH data symbols (not DMRS symbols), puncturing results in non-orthogonal multiplexing and should not be used, Otherwise, the PUCCH data symbols can be punctured and the orthogonality preserved.

Example: Partial PDSCH/PUSCH subframes, punctured PDSCH, PUSCH (does not affect DMRS symbols or ACK/NACK symbols), and PUCCH (does not affect DMRS) formats can be considered.

In option 3, changes in HARQ timing or A-SRS transmission timing may be considered. Suppose the SRS trigger is sent in DCI in subframe n. If DL grant is also present in subframe n, both PUSCH ACK/NACK and SRS need to be sent in subframe n+k, which can cause collisions. Therefore, it may be considered to reuse the ACK/NACK timing in eIMTA to change the ACK/NACK timing so that it is within a subsequent subframe. Alternatively, the SRS may be sent after n+k in the first subframe with the allowed SRS switch (eg, special subframe) and there is no collision. Like the eLAA SRS trigger, the SRS trigger may also be associated with the timing offset, which indicates to the UE different opportunities for SRS switching. The eLAA has 3 bits to indicate the offset to subframe n+k with respect to the number of subframes, ie 000 is for a subframe offset of 0, and so on. Several bits can be considered for SRS switching, such as one or two bits. Also for SRS switching, the offset relates to the SRS transmission opportunity set to the UE, which corresponds to T _SRS,1 , T _offset,1 and k _SRS in TS36.213.

Yet another embodiment for collision handling is to enable PUCCH/PUSCH transmission on the CC to switch to. If the UE switches to CC for SRS, the UE stays in CC for another UL Tx until the next switch occurs. The good thing is that there is no drop in the transmission. This effectively results in UL fast carrier switching.

Multiple antenna support for SRS
For TDD systems, sounding is very important for improving system performance. DL CSI relies heavily on sounding. Since all antennas are used for DL reception, it is necessary to support sounding for all UE antennas.

With different DL and UL capabilities, the UE may sound one or several antennas at a time. Below is a summary of the different UL capabilities:
2Rx in DL
UL does not support 1Tx, transmit antenna selection
2Tx at UL
Supports 1Tx, transmit antenna selection in UL
4Rx in DL
UL does not support 1Tx, transmit antenna selection
2Tx in UL, does not support transmit antenna selection
4Tx at UL
Supports 1Tx, transmit antenna selection in UL
Supports 2Tx and transmit antenna selection in UL.

For cases 1a, 2a, 2b, it is not possible to sound all antennas, because transmit antenna selection is not supported, ie the UE cannot transmit on other antennas. These cases are excluded in the considerations below.

For two antennas, the UE can support sounding of two antennas through UL 2x2 MIMO (case 1b) or two antenna switching (case 1c), which are already supported in the specifications for UEs of different capabilities. With the introduction of switching based on SRS carriers, the sounding of two antennas is further influenced by the standard through RRC configuration for P-SRS and RRC configuration for A-SRS plus DCI indication. Can be run on carriers without PUSCH without.

In case 2c, sounding with all four Tx antennas is already supported in R13 and can be combined with SRS carrier based switching without further standard impact. However, there are few UEs that support 4Tx in UL in actual networks. It may take a long time before a UE with uplink 4Tx capability can become popular. For 4Rx in DL, typical UE capabilities should be cases 2d and 2e. Therefore, in order to sound all four uplink antennas, cases 2d and 2e should be the main focus for SRS extension.

For 4 antennas, if the UE has only 1 UL Tx antenna capability (Case 2d) or 2 UL Tx antenna capability (Case 2e), switching of 4 antennas should be incorporated to sound all antennas. Is. Switching of four antennas includes CCs with PUSCH or CCs without PUSCH, and is for sounding all CCs.

Sounding enhancements in the frequency and spatial domains significantly improve DL throughput, which is the motivation for switching WI based on SRS carriers. It has been proposed to incorporate four antenna switching (cases 2d and 2e) for SRS with carrier switching.

In Rel-13, the Tx antenna is switched at every SRS transmission point for P-SRS because of switching between the two antennas. Switching of 2Tx antennas on one carrier is performed based on a predetermined pattern calculated from the RRC-configured parameters. For a UE with 4 antennas, the antenna switching should include all 4 antennas. With carrier switching in Rel-14, the UE can also perform antenna switching for SRS transmission combined with carrier-based switching. Therefore, sounding can be performed with different carriers and antennas.

Antenna switching for SRS transmission with carrier switching may be based on a predetermined pattern calculated from RRC-configured parameters. The mechanism is similar to the 2Tx antenna switching supported in Rel-13. The predetermined switching pattern should facilitate sounding of all antennas. All antennas should have an opportunity for SRS transmission on CC with PUSCH or CC without PUSCH. Enabling the antenna switching by carrier switching can be set by RRC. For carrier switching for SRS transmission, antenna switching is executed based on a predetermined pattern.

Both P-SRS and A-SRS are supported for switching based on SRS carrier. For CC with PUSCH or CC without PUSCH, SRS should be configured separately by RRC. For CC with PUSCH, the conventional sounding procedure can be reused in all cases except 2d, 2e. For Cases 2d and 2e, a new antenna switching scheme can be defined to support the sounding of all four Tx antennas. In case 2e, the four Tx antennas can be divided into two groups with two antennas in each group. Antenna switching can be performed both between antenna groups and between antennas within a group.

For CC without PUSCH, a new sounding procedure can be defined to handle antenna combination and carrier switching. A UL 4x4 MIMO capable UE can sound 4 antennas at a time. For UEs with 1 UL Tx antenna capability, 4 Tx antenna switching is used to sound one antenna at a time. At RF tuning times, frequent carrier switching results in greater frequency tuning time overhead. To support 4Tx antenna switching, the overhead of switching antenna+carrier should be improved.

The latency of sounding all antennas and carriers can be high. To reduce the sounding latency, it is more preferable to sound all four Tx antennas on the CC when carrier switching continues for SRS on the CC. SRSs from 4 Tx antennas should be transmitted on different symbols in short intervals to reduce latency. In a TDD system, at least in CC without PUSCH, multiple symbols in a subframe (eg, all four additional symbols in UpPTS) can be used for SRS transmission of four Tx antennas by the same UE. In current TS 36.213, this is: "For TDD serving cells, if the UE is configured with 2 or 4 additional SC-FDMA symbols in the UpPTS of a given serving cell, all can be used for SRS transmission, For SRS with trigger type 0, at most two SC-FDMA symbols can be assigned to the same UE from among the additional SC-FDMA symbols configured in UpPTS." If such a restriction is removed, all four additional symbols in UpPTS can be used by the same UE for SRS transmission. Furthermore, for the trigger type 0, when SoundingRS-UL-ConfigDedicatedUpPTsExt is set and SoundingRS-UL-ConfigDedicated is set, both shall be used. If SoundingRS-UL-ConfigDedicatedAperiodicUpPTsExt and SoundingRS-UL-ConfigDedicated are set for trigger type 1, both shall be used.

There are several options for SRS switching requirements:

1) There is no requirement for maximum interruption.

2) Maximum interruption = 1 subframe. This means that SRS switching does not affect the next subframe, in which case the A/N is unaffected and the network carefully configures the appropriate UE for SRS switching. If the break is limited to one subframe, then the break is only within the last symbol of the special subframe or UL subframe if it has a consistent TDD UL/DL setting. The special subframe does not carry A/N. The SRS on the last symbol of the UL subframe does not affect the A/N. For FDD+TDD without timing alignment between TDD and FDD, if the switching results in two lost UL subframes in FDD, this does not result in switching from FDD CC to TDD CC. Good.

3) Maximum interruption = 2 subframes.

Additionally (or as an alternative), if the requirement of "A/N loss rate not greater than 0.5%" is introduced, the network is completely free to decide how SRS switching will be performed. Other than that, the standard does not have to impose any other strict constraints, but it entrusts the network to determine the settings so that the A/N loss rate requirements are met. Although it does not actually solve the interruption or collision problem, it limits the negative effects of interruption and collision.

FIG. 55 shows a block diagram of an example processing system 5500 for performing the methods described herein, which may be located in a host device. As shown, processing system 5500 includes processor 5504, memory 5506, and interfaces 5510-5514, which may (or may not) be configured as shown in FIG. 55. Processor 5504 may be any component or collection of components adapted to perform computational and/or other processing tasks, and memory 5506 stores programming and/or instructions for execution by processor 5504. May be any component or collection of components adapted to In an embodiment, memory 5506 includes non-transitory computer readable media. Interfaces 5510, 5512, 5514 may be any component or collection of components that enables processing system 5500 to communicate with other devices/components and/or users. For example, one or more of interfaces 5510, 5512, 5514 may be adapted to communicate data, control or management messages from processor 5504 to applications installed on host devices and/or remote devices. As another example, one or more of interfaces 5510, 5512, 5514 allow a user or user device (eg, a personal computer (PC), etc.) to interact/communicate with processing system 5500. May be adapted as The processing system 5500 may include additional components not shown in FIG. 55, such as long term storage (eg, non-volatile memory, etc.).

In some embodiments, processing system 5500 is included in a network device that accesses or is otherwise part of a telecommunications network. In one example, the processing system 5500 is within a network-side device within a wireless or wired telecommunications network, such as a base station, relay station, scheduler, controller, gateway, router, application server, or other device within a telecommunications network. is there. In another example, the processing system 5500 is adapted to access a mobile station, user equipment (UE), personal computer (PC), tablet, wearable communication device (eg, smartwatch, etc.) or telecommunications network. Like other devices, in user-side devices that access wireless or wired telecommunications networks.

In some embodiments, one or more of interfaces 5510, 5512, 5514 connect processing system 5500 to a transceiver adapted to send and receive signaling over a telecommunications network. FIG. 56 shows a block diagram of a transceiver 5600 adapted to send and receive signaling on a telecommunications network. The transceiver 5600 may be installed in the host device. As shown, the transceiver 5600 includes a network side interface 5602, a coupler 5604, a transmitter 5606, a receiver 5608, a signal processor 5610, and a device side interface 5612. The network side interface 5602 may include any component or collection of components adapted to send or receive signaling over a wireless or wireline telecommunications network. Coupler 5604 may include any component or collection of components adapted to facilitate bi-directional communication on network side interface 5602. The transmitter 5606 may be any component or set of components adapted to convert a baseband signal into a modulated carrier signal suitable for transmission on the network side interface 5602 (eg, upconverter, power amplifier, etc.). May be included. Receiver 5608 may include any component or set of components (eg, down converters, low noise amplifiers, etc.) adapted to convert a carrier signal received on network side interface 5602 to a baseband signal. .. The signal processor 5610 may include any component or collection of components adapted to convert a baseband signal into a data signal suitable for communication on the device-side interface 5612 and vice versa. The device-side interface 5612 is adapted to communicate data signals between the signal processor 5610 and components within the host device (eg, processing system 5500, local area network (LAN) ports, etc.). It may include any component or collection of components.

Transceiver 5600 may send and receive signaling on any type of communication medium. In some embodiments, transceiver 5600 sends and receives signaling on a wireless medium. For example, transceiver 5600 may be a cellular protocol (eg, long-term evolution, LTE, etc.), a wireless local area network (WLAN) protocol (eg, Wi-Fi, etc.) or other It may be a wireless transceiver adapted to communicate according to a wireless telecommunications protocol, such as a wireless protocol of some kind (eg Bluetooth, near field communication (NFC), etc.). In such an embodiment, network-side interface 5602 includes one or more antenna/radiating elements. For example, the network side interface 5602 is a multi-layer communication, for example, a single input multiple output (SIMO), a multiple input single output (multiple input single output, MISO), a multiple It may include a single antenna configured for multiple input multiple output (MIMO), etc., multiple separate antennas or a multi-antenna array. In another embodiment, the transceiver 5600 sends and receives signaling on a wired medium, eg, twisted pair cable, coaxial cable, optical fiber, etc. A particular processing system and/or transceiver may utilize all of the illustrated components or only a subset of the components, and the level of integration may vary from device to device.

The following references are incorporated by reference as if reproduced in full.
TS36.211 v13.0.0 http://www.3gpp.org/dynareport/36211.htm
TS36.213 v13.01 http://www.3gpp.org/dynareport/36213.htm
TS36.331 v13.0.0 http://www.3gpp.org/dynareport/36331.htm
TS36.212 v13.1.0 http://www.3gpp.org/ftp//Specs/archive/36_series/36.212/36212-d10.zip
TS36.321 v13.0.0 http://www.3gpp.org/dynareport/36321.htm

According to a first embodiment, a method for reference signal transmission is provided. In this example, it is provided that the method comprises the step of receiving one or more downlink transmissions on the first aggregated component carrier set. The UE may simultaneously transmit uplink signals on less than all component carriers in the first aggregated component carrier set. The method further comprises transmitting sounding reference signal (SRS) symbols on different component carriers in the first set of aggregated component carriers during different time periods. An apparatus for performing the method is also provided.

In an example of the first embodiment, the step of transmitting the SRS symbol comprises the step of transmitting radio resource control from the base station before transmitting the one or more SRS symbols on the first component carrier within the set of aggregated component carriers. RRC) message is received. The RRC message specifies the periodic SRS configuration parameters for transmitting one or more SRS symbols on the first component carrier. In such an example, the step of transmitting the SRS symbol may comprise one or more on the first component carrier during a periodic interval within the sequence of periodic intervals according to the periodic SRS configuration parameter specified by the RRC message. The method further comprises periodically transmitting SRS symbols. The RRC message may specify a period between consecutive intervals in the sequence of periodic intervals. Alternatively, the RRC message may specify orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbol positions where one or more SRS symbols should be transmitted on the component carriers.

In another example of the first embodiment, transmitting SRS symbols on different component carriers comprises transmitting one or more SRS symbols on the first component carrier in the set of aggregate component carriers, Receiving a downlink control information (DCI) message from the base station. The DCI message specifies SRS configuration parameters for transmitting one or more SRS symbols on the first component carrier. In such an example, transmitting the SRS symbol further comprises transmitting one or more SRS symbols aperiodically on the first component carrier according to the SRS configuration parameter specified by the DCI message. In one case of this example, the DCI message specifies the transmit power level for one or more SRS symbols. In the same or other cases of this example, the DCI message triggers an aperiodic transmission of one or more SRS symbols on the first component carrier. In any one of the previous cases of this example or another case, the DCI message is received on a second component carrier different from the first component carrier, and the DCI message on the second component carrier is Reception triggers inter-carrier transmission of one or more SRS symbols on the first component carrier. In any one or another of the previous cases of this example, the UE receives the DCI message on the UE's primary component carrier and one or more SRS symbols are transmitted on the UE's secondary component carrier. To be done. In any one of the above cases of this example or another case, the UE receives the DCI message on the common search space of the physical downlink control channel (PDCCH) of the UE. In any one or another of the previous cases of this example, the DCI message has a DCI length equal to that associated with DCI format 0.

In another example of the first embodiment, the method is a radio resource that specifies a downlink control information (DCI) message format for signaling SRS configuration parameters on a physical downlink control channel (PDCCH) from a base station. The method further includes receiving a control (RRC) message. In such an example, the step of transmitting the SRS symbol comprises monitoring the PDCCH for a DCI message having a DCI message format specified by the RRC message and signaling by a DCI message having the DCI message format specified by the RRC message. Transmitting one or more SRS symbols on the first component carrier in the first aggregated component carrier set according to the configured SRS configuration parameters. In one instance of this example, the RRC message specifies a particular DCI message format to indicate the SRS transmit power level. In the same or other cases of this example, the RRC message specifies a particular DCI message format for triggering aperiodic SRS symbol transmission. In any one or another of the previous cases of this example, the RRC message specifies a particular DCI message format for triggering inter-carrier transmission of SRS symbols.

In all cases of all the examples of the first embodiment or another example of the first embodiment, the method further comprises transmitting an uplink control message indicating the uplink carrier aggregation capability of the UE.

In another example of the first embodiment, the method further comprises receiving a downlink control signal specifying a dual connectivity cell group configuration constraint from the network controller. The dual connectivity cell group configuration constraint is that (i) the UE, during the set of periods, from the source component carrier in the first aggregated component carrier set monitored by the first base station to the second Prohibiting switching to a target component carrier in a second aggregated component carrier set monitored by the base station, and (ii) the UE is monitored by the second base station during the set period. Switching from a source component carrier in a second aggregated component carrier set to a target component carrier in a first aggregated component carrier set monitored by the first base station; Do both. In one example of this example, the step of transmitting SRS symbols comprises transmitting any SRS symbol on a component carrier within a second aggregated set of component carriers during any period within the set of periods. Does not use the UE's first transmit chain (TX chain), but via the first TX chain different component carriers in the first aggregated component carrier set during different periods in the set of periods UE for transmitting at least a first SRS symbol above, and for transmitting any SRS symbol on a component carrier in a second aggregated component carrier set during any period in the set of periods UE Of at least a second component on a different component carrier in a second set of aggregated component carriers during a different period in the set of periods without using a second TX chain of Transmitting SRS symbols.

In another example of the first embodiment, the method comprises a network controller instructing a UE to switch between component carriers in a first aggregated component carrier set according to a periodic interval. The method further comprises the step of receiving a higher layer control signal that specifies a physical uplink SRS switching setting. In this example, the step of transmitting SRS symbols comprises transmitting at least one SRS symbol on each component carrier within the set of aggregated component carriers according to the periodic uplink SRS switching setting during the first set of periods. Transmitting, receiving from a network controller a Medium Access Control (MAC) message deactivating at least one component carrier in the aggregated set of component carriers, and at least during a second set of periods. Does not transmit any SRS symbols on one deactivated component carrier, and during the set of the second period, each remaining component in the set of aggregated component carriers according to the periodic uplink SRS switch settings. Transmitting at least one SRS symbol on the carrier.

In another example of the first embodiment, the method further comprises receiving a single downlink control message and at least the first field. A single downlink control message contains multiple SRS commands for multiple UEs. The method further includes identifying the position of the SRS command for the UE among the multiple SRS commands in a single downlink control message based on the number of bits indicated by the field. In one case of this example, the first field is a field in a single downlink control message. In the same or other cases of this example,

In any one or another of the previous cases of this example, the first field is received via higher layer signaling.

In any one of the above cases of this example or another case, the SRS command indicates the transmit power level to be used when transmitting the SRS symbols.

In any one of the previous cases of this example or another case, the SRS command indicates a condition for triggering an aperiodic SRS symbol transmission.

In another example of the first embodiment, one or more downlink transmissions are transmitted by a single base station. In one case of this example, the one or more downlink transmissions include at least a first downlink transmission on a first component carrier and a second downlink transmission on a second component carrier. .. The first downlink transmission and the second downlink transmission are transmitted by the same or different base stations during a common period. In such cases, the first downlink transmission may correspond to the primary cell and the second downlink transmission may correspond to the secondary cell. Alternatively, in such cases, the first downlink transmission may correspond to a different secondary cell than the second downlink transmission.

According to a second embodiment, a method for reference signal reception is provided. In this example, the method includes transmitting one or more downlink signals to a user equipment (UE) on the first aggregated component carrier set. The UE may not transmit uplink signals simultaneously on all component carriers in the first aggregated component carrier set. The method further includes receiving sounding reference signal (SRS) symbols from the UE on different component carriers in the first aggregated component carrier set during different time periods. An apparatus for performing the method is also provided.

In an example of the second embodiment, the RRC message specifies a period between consecutive intervals in the sequence of periodic intervals.

In the same or another example of the second embodiment, the RRC message is an Orthogonal Frequency Division Multiplex (OFDM) or Single Carrier Frequency Division Multiple Access (SC-FDMA) in which one or more SRS symbols are to be transmitted on the component carriers. ) Specify the symbol position.

In another example of the second embodiment, the method sends a downlink control information (DCI) message to a UE that specifies SRS configuration parameters for transmitting one or more SRS symbols on the first component carrier. And receiving SRS symbols from the UE on the first component carrier during the first time period. The SRS symbol is transmitted according to the SRS setting parameter specified by the DCI message. In one instance of this example, the DCI message specifies the transmit power level for SRS symbols. In other cases of this example, the DCI message specifies aperiodic transmission of SRS symbols. In any one of the previous cases of this example or another case, the DCI message is received on a second component carrier different from the first component carrier, and the DCI message on the second component carrier is Reception triggers inter-carrier transmission of SRS symbols on the first component carrier.

In another example of the second embodiment, the method sends a Radio Resource Control (RRC) message to the UE that specifies a downlink control information (DCI) format to indicate sounding reference signal (SRS) configuration parameters. A step of transmitting a DCI message having a DCI format to the UE, and a step of receiving an SRS symbol from the UE after transmitting a DCI message having the DCI format to the UE, the DCI message being for the UE an SRS Commanding to transmit the SRS symbols according to the set parameters. In such cases, the RRC message is a specific DCI message format to indicate the SRS transmit power level, a specific DCI message format to trigger aperiodic SRS symbol transmission, and/or inter-carrier transmission of SRS symbols. Specifies a specific DCI message format for triggering.

In another example of the second embodiment, the method comprises: receiving from the UE an uplink control message indicating an uplink carrier aggregation capability of the UE; and an uplink carrier switching setting based on the UE carrier aggregation capability. And assigning to the UE, based on the uplink carrier switching settings, sending a downlink control signal to the UE to instruct the UE to transmit SRS symbols on the aggregated component carrier set, and Is further included. In one case of this example, the uplink carrier switching configuration is at least a first component assigned to carry the UE's SRS symbols and physical uplink control channel/physical uplink shared channel (PUCCH/PUSCH) transmissions. Designate a carrier and at least a second component carrier that is allocated to carry the UE's Sounding Reference Signal (SRS) symbol transmissions, but not the UE's PUCCH/PUSCH transmissions. In such a case, the uplink carrier switching configuration continues to the UE for at least one of the first SRS symbol and PUSCH or PUCCH signal on the first component carrier during the initial period and for the initial period. The second SRS symbol on the second component carrier during a later period may be instructed to be transmitted. In another instance of this example, the uplink carrier switch settings specify the periodic intervals for switching from the source component carrier to the target component carrier.

In another example of the second embodiment, the method further comprises sending a downlink control signal to the UE that specifies a dual connectivity cell group configuration constraint. The first aggregated component carrier set is at least a first aggregated component carrier set monitored by a first base station and a second aggregated component carrier monitored by a second base station. And a dual connectivity cell group configuration constraint is that the (i) UE is configured such that the UE aggregates from a source component carrier in a first aggregated component carrier set during a set of time periods to a second aggregated component carrier set. Disabling switching to a target component carrier in the set of configured component carriers, and (ii) the UE, during the set of time periods, from the source component carrier in the second aggregated component carrier, Both prohibiting switching to the target component carrier within the set of two aggregated component carriers.

In another example of the second embodiment, the method further comprises receiving an uplink control message from the UE. The uplink control message includes two or more bits indicating the uplink radio frequency (RF) frequency alignment delay of the UE for switching from the source component carrier to the target component carrier, and the downlink frequency alignment delay of the UE is the uplink of the UE. A single value set to either a first value indicating equality to the frequency alignment delay or a second value when the downlink frequency alignment delay of the UE is equal to 0. In this example, the method comprises assigning an uplink carrier switching setting to the UE based on the UE's downlink frequency alignment delay and, for the UE, a first aggregated based on the uplink carrier switching setting. Sending a downlink control signal to the UE instructing to send SRS symbols on the set of component carriers. In one case of this example, the uplink control message indicates a particular uplink frequency alignment delay for switching from a first RF band containing the source component carrier to a second RF band containing the target component carrier. In such cases, the first RF band may be different than the second RF band and/or the two or more bits of the uplink control message may be orthogonal frequency division multiplexed (OFDM) or single carrier frequency division. It may indicate the UE's uplink RF frequency alignment delay as a number of multiple access (SC-FDMA) symbols.

In another example of the second embodiment, the method comprises, by the base station, a single downlink control message to both the first UE and the second UE and a first field to the first UE. And a second field to a second UE. The single downlink control message carries a first SRS command for the first UE and a second SRS command for the second UE. The first field indicates the number of bits used to indicate the first SRS command in a single downlink control message, and the second field the second field in a single downlink control message. Indicates the number of bits used to indicate the SRS instruction. In one case of this example, the first field and the second field are fields within a single downlink control message. In another case of this example, the first field and the second field are transmitted to the first UE and the second UE respectively via higher layer signaling. In any one or another of the previous cases of this example, the first SRS command and the second SRS command are used by the first UE and the second UE respectively when transmitting SRS symbols. And/or the first SRS command and the second SRS command indicate SRS trigger conditions for triggering SRS symbol transmissions by the first UE and the second UE, respectively.

According to a third embodiment, a method for transmitting uplink signals is provided. In this example, the method includes transmitting a first uplink signal in a first subframe on a first component carrier during a first period. The first uplink signal carries at least a first Sounding Reference Signal (SRS) symbol. The method further includes switching from the first component carrier to the second component carrier according to the SRS switching schedule. Uplink RF frequency alignment delay is associated with switching from the first component carrier to the second component carrier. The method further includes transmitting a second uplink signal in the second subframe on the second component carrier during the second period. The second uplink signal carries at least one of the second SRS symbol and the random access preamble.

In an example of the third embodiment, the method further comprises sending, by the UE, an uplink control message specifying a duration of the uplink RF frequency alignment delay to the base station. In one example of this example, the uplink control message comprises two or more bits that indicate the duration of the UE's RF frequency alignment delay and the UE's downlink RF frequency alignment delay is the UE's uplink RF frequency alignment delay. A first value indicating equality, or a single bit set to either a second value when the UE's downlink RF frequency alignment delay is equal to zero. In another example of this example, two or more bits of the uplink control message are the UE's uplink RF frequency alignment as the number of orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbols. Indicates a delay. In such a case, the UE may perform a physical downlink on an orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbol of a second component carrier that overlaps in time with the downlink RF frequency alignment delay. It is not necessary to monitor or receive the link control channel (PDCCH) or the physical downlink shared channel (PDSCH).

In another example of the third embodiment, the step of transmitting the second uplink signal in the second subframe on the second component carrier during the second period comprises the uplink RF frequency alignment delay. Puncturing the portion of the second uplink signal corresponding to the duration.

According to a fourth embodiment, a method for reference signal switching is provided. In this example, the method includes transmitting a first sounding reference signal (SRS) symbol on the primary component carrier during the first time period. The UE that transmitted the SRS symbol is configured to transmit both the second SRS symbol on the secondary component carrier during the second period and the uplink control message on the primary carrier during the second period. Scheduled. This results in scheduling collisions between SRS symbols and uplink control messages. The method does not transmit the second SRS symbol on the secondary component carrier during the second period and transmits the uplink control message on the primary component carrier during the second period when the uplink control message meets the criteria. The method further includes the step of transmitting.

In an example of the fourth embodiment, the uplink control message meets the criteria when the uplink control message includes an acknowledgment or a negative acknowledgment (ACK/NACK) message. In one instance of such an example, the uplink control message meets the criteria when the uplink control message includes channel state information (CSI).

In any one or another of the previous cases of this example, or quite another example, the method transmits a second SRS symbol on the secondary carrier during a third period that follows the second period. The method further includes steps. The third period of time may be the next available opportunity to transmit the second SRS symbol.

According to a fifth embodiment, a method for transmitting an uplink signal is provided. In this example, the method includes receiving from the base station a control signal indicating that the aggregated set of component carriers is assigned to a timing advance group (TAG). At least the first component carrier assigned to the TAG does not support physical uplink control channel (PUCCH) signaling or physical uplink shared channel (PUSCH) signaling. The method further includes transmitting sounding reference signal (SRS) symbols on the one or more component carriers assigned to the TAG according to a timing advance parameter associated with the TAG.

In an example of the fifth embodiment, the method sends a random access preamble to a base station to request timing advance for a first component carrier, and timing advance for the first component carrier. And receiving no control signal indicating from the base station from the base station, transmitting no PUSCH signaling on the first component carrier during the first period, and transmitting no PUCCH signaling during the first period according to the timing advance. Transmitting a first Sounding Reference Signal (SRS) symbol on the first component carrier therein. In one instance of such an example, the method further comprises transmitting a second SRS symbol on the second component carrier during the second period. In such a case, the UE does not transmit any uplink signaling on the second component carrier during the first period, and transmits the first SRS symbol on the first component carrier during the first period. And does not transmit any uplink signaling on the first component carrier during the second period and transmits the second SRS symbol on the second component carrier during the second period. In such a case, the UE does not receive an explicit command to switch from the first component carrier to the second component carrier, and based on a preset SRS switching interval during the second period. The second SRS may be transmitted on the second component carrier, in which case the preset SRS switching interval is aggregated for the UE during different periods within a series of periodically occurring periods. There may be periodic switching intervals that require SRS symbols to be transmitted on different subsets of component carriers within the set of reserved component carriers. In any one of the previous cases of this example or another case, the method directs the UE to transmit a second SRS symbol on a second component carrier during a second period. The method further includes receiving a switching command from the base station. The switching instruction may be received in a downlink control information (DCI) message.

According to a sixth embodiment, a method for receiving an uplink signal is provided. In this example, the method comprises transmitting a downlink signal to the UE on the aggregated set of component carriers and on a first component carrier in the aggregated set of component carriers during a first period of time. Receiving a first Sounding Reference Signal (SRS) symbol from the UE and receiving a second SRS symbol from the UE on a second component carrier within the set of component carriers aggregated during the second time period And steps. The second component carrier is different than the first component carrier.

In an example of the sixth embodiment, the first SRS symbol does not receive any uplink signaling from the UE on the second component carrier during the first period, and the first component during the first period. Received from the UE on the carrier, the second SRS symbol does not receive any uplink signaling from the UE on the first component carrier during the second period, and the second component carrier during the second period. Received from the UE above.

In that example or other example of the sixth embodiment, the method comprises a switching command instructing the UE to transmit the second SRS symbol on the second component carrier during the second period. The method further includes transmitting to the UE.

In any of the above cases of the sixth embodiment or other examples, the first component carrier supports physical uplink shared channel (PUSCH) transmission. In such an example, the second component carrier may not support PUSCH transmission.

In any of the above cases of the sixth embodiment or any of the other examples, the method is instructed to send the third SRS symbol on a different component carrier that does not support PUSCH and/or PUCCH transmission. If not, further comprising transmitting at least one of a third SRS symbol, PUSCH and PUCCH on the first component carrier during the third period.

In any of the above cases of the sixth embodiment or other examples, the first component carrier is frequency division duplex (FDD) and the second component carrier is time division duplex (TDD). Or in an unpaired spectrum. Alternatively, the first component carrier and the second component carrier may be time division duplex (TDD) or may be in an unpaired spectrum.

In any of the above cases of the sixth embodiment or other examples, the method comprises a first downlink transmission on a first component carrier and a second downlink transmission on a second component carrier. Link transmission and the transmission parameter for the first downlink transmission is derived from the received signal information corresponding to the first SRS symbol, and the transmission parameter for the second downlink transmission is , Derived from received signal information corresponding to the second SRS symbol.

In any or other of the aforementioned cases of the sixth embodiment, the UE does not transmit any physical uplink shared channel (PUSCH) signaling on the first component carrier during the first period, And does not transmit any physical uplink control channel (PUCCH) signaling on the first component carrier during the first period, and transmits SRS configuration parameters on the first component carrier during the first period.

According to a seventh embodiment, a method for transmitting control signals is provided. In this example, the method includes transmitting a control signal to the UE. The control signal indicates that the aggregated set of component carriers is assigned to a timing advance group (TAG). At least the first component carrier assigned to the TAG does not support physical uplink control channel (PUCCH) signaling and physical uplink shared channel (PUSCH) signaling, and the control signal is associated with the TAG to the UE. Prompts to send a Sounding Reference Signal (SRS) symbol on one or more component carriers assigned to the TAG according to the timing advance parameter.

According to a seventh embodiment, a method for transmitting control signals is provided. In this example, the method includes transmitting a control signal to the UE. The control signal indicates that the aggregated set of component carriers is assigned to a timing advance group (TAG). At least the first component carrier assigned to the TAG does not support physical uplink control channel (PUCCH) signaling and physical uplink shared channel (PUSCH) signaling, and the control signal is associated with the TAG to the UE. Prompts to send a Sounding Reference Signal (SRS) symbol on one or more component carriers assigned to the TAG according to the timing advance parameter.

In an example of the seventh embodiment, the control signal is a downlink control information (DCI) message.

In another example of the seventh embodiment, the method further comprises receiving at least one of a Random Access Channel (RACH) message and SRS symbols on a secondary component carrier that does not carry the PUCCH or PUSCH transmissions of the UE. ..

In one case of this example, the RACH message is sent on a non-contention based access channel. In such cases, the RACH message and SRS symbols may be received on the secondary component carrier. In other cases of this example, the method further comprises receiving a PUCCH or PUSCH transmission from the UE on the primary component carrier prior to receiving the RACH message and/or SRS symbols on the secondary component carrier. In such cases, the UE switches from the primary component carrier to the secondary component carrier after sending the PUCCH or PUSCH transmission on the primary component carrier. In such cases, the method may further include sending a downlink control command (DCI) message to the UE instructing the UE to switch from the primary component carrier to the secondary component carrier.

According to an eighth embodiment, there is provided a method for receiving an uplink signal. In this example, the method includes receiving a random access channel (RACH) transmission from a user equipment (UE). RACH transmission does not require grants for physical uplink control channel (PUCCH) resources, and does not request grants for physical uplink shared channel (PUSCH) resources, and requests timing advance for component carriers. To do. The method comprises transmitting a control signal indicating a timing advance for a component carrier to a UE, receiving no PUSCH signaling on the component carrier, and receiving no PUCCH signaling on the component carrier, according to the timing advance. , Receiving one or more Sounding Reference Signal (SRS) symbols from the UE on the component carrier.

According to a ninth embodiment, a method for reference signal transmission is provided in this embodiment, the method comprising: reporting a user equipment (UE) component carrier capability to a base station; and one or more downlinks. Configuring a UE based on information from a base station for a first set of component carriers for link reception, and a first set of component carriers in the first set of component carriers for one or more uplink transmissions. Configuring the UE based on information from the base station for a subset of one component carrier. The one or more transmissions include at least one of a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH) or a sounding reference signal (SRS) symbol transmission. The UE may simultaneously transmit the uplink signal on all component carriers within the first subset of component carriers. The method does not configure a second subset of component carriers for PUSCH/PUCCH, and eNB for a second subset of component carriers within the first set of component carriers for one or more SRS transmissions. Further comprising configuring the UE based on the information from, and transmitting SRS symbols on different component carriers in the first subset of component carriers and the second subset of component carriers during different time periods.

In an example of the ninth embodiment, the number of component carriers in the first subset of component carriers and the second subset of component carriers exceeds the indicated uplink carrier aggregation capability of the UE. In the same or different cases of this example, the number of component carriers in the second subset of component carriers exceeds the indicated uplink carrier aggregation capability of the UE.

According to a tenth embodiment, a method for reference signal transmission is provided. In this example, the method includes transmitting a first uplink signal on a first component carrier during a first time period. The first uplink signal carries at least a first Sounding Reference Signal (SRS) symbol. The method comprises switching from a first component carrier to a second component carrier according to a switching parameter for an SRS switching schedule and transmitting a second uplink signal on the second component carrier during a second period. And the step of performing. The second uplink signal carries at least one of the second SRS symbol and the random access preamble, the transmission occurring after the uplink RF frequency alignment time.

In an example of the tenth embodiment, the switching parameter is determined by the settings received before the first time period.

In another example of the tenth embodiment, the switching parameter is determined by the messaging received during the first time period.

According to an eleventh embodiment, a method for reference signal transmission is provided. The method includes receiving one or more downlink transmissions on the aggregated set of component carriers and a first component carrier on the aggregated set of component carriers during a first period of time At least one of the sounding reference signal (SRS) symbols and at least one of the physical uplink shared channel (PUSCH) signal and the physical uplink control channel (PUCCH) signaling. At least one of the parameters for the SRS symbol is generated based on the parameters for the PUSCH. The method does not send any PUSCH and PUCCH signaling on the second component carrier during the second period, and at least on the second component carrier within the set of aggregated component carriers during the second period. The method further comprises transmitting the second SRS symbol. Unlike the first component carrier, the second component carrier does not generate any of the parameters for the SRS symbol based on the parameters for any PUSCH.

In an example of the eleventh embodiment, the method receives a control signal from a base station indicating that the second component carrier is assigned to a timing advance group (TAG), and according to a timing advance parameter related to TAG. Transmitting sounding reference signal (SRS) symbols on one or more component carriers assigned to the TAG.

While the description has been given in detail, it should be understood that various changes, substitutions and changes can be made without departing from the spirit and scope of this disclosure, which is defined by the appended claims. .. Furthermore, any process, machine, manufacture, composition of matter, means, method or step now present or later developed, performs substantially the same function as, or is substantially the same as, the corresponding embodiment described herein. The scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily recognize from the disclosure that the results may be achieved. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

For a more complete understanding of the present invention and its advantages, reference is now made to the following description in conjunction with the accompanying drawings.
It is a figure of the wireless-communications network of an example. FIG. 3 is a diagram of a network for supporting SRS switching. It is a figure of a communication sequence of an example for setting up a periodic SRS change schedule. 3 is a flowchart of an example method for transmitting SRS symbols. 6 is a flowchart of an example method for performing channel estimation based on SRS symbols. FIG. 7 is a diagram of an example communication sequence for configuring or otherwise triggering aperiodic SRS symbol transmission. 7 is a flowchart of another example method for transmitting SRS symbols. 6 is a flowchart of another example method for performing channel estimation based on SRS symbols. It is a figure of the communication sequence of the Example for setting the DCI message format relevant to an SRS setting parameter. 6 is a flowchart of yet another example method for transmitting SRS symbols. 7 is a flowchart of yet another example method for performing channel estimation based on SRS symbols. It is a figure of the communication sequence of the Example for assigning an uplink carrier switching setting based on the uplink carrier aggregation capability of UE. 6 is a flowchart of an example method for assigning an uplink carrier switching setting based on a UE's uplink carrier aggregation capability. 3 is a flowchart of an example method for transmitting SRS symbols. FIG. 3 is a diagram of a network for supporting SRS switching. 3 is a flowchart of an example method for transmitting SRS symbols. FIG. 7 is a diagram of transmissions that occur before and immediately after the UE 210 switches from a source component carrier to a target component carrier. FIG. 7 is a diagram of transmissions that occur before and immediately after the UE 210 switches from a source component carrier to a target component carrier. FIG. 5 is a diagram of a frame format of an uplink control message signaling UE uplink and downlink RF frequency alignment delays. 6 is a flow chart of an example method for signaling UE uplink and downlink RF frequency alignment delays. 6 is a flowchart of an example method 2100 for determining UE uplink and downlink RF frequency alignment delays. It is a figure of the communication sequence of the Example for adapting a periodic SRS switching schedule according to the deactivation of a component carrier. 6 is a flow chart of an example method for adapting a periodic SRS switching schedule in response to component carrier deactivation. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. FIG. 6 is a diagram of a frame format for a control message that carries an SRS command. 6 is a flowchart of an example method for finding an SRS command in a control message. 6 is a flowchart of another example method for performing channel estimation based on SRS symbols. FIG. 6 is a diagram of uplink transmissions that occur before and immediately after a UE switches from a source component carrier to a target component carrier. 6 is a flowchart of an example method for puncturing an uplink signal to compensate for uplink RF frequency alignment delay. FIG. 6 is a diagram of transmissions that occur before and immediately after a UE switches from a source component carrier to a target component carrier. 6 is a flowchart of an example method for collision handling during SRS switching. FIG. 3 is a diagram of a network for supporting SRS switching. FIG. 3 is a diagram of a network for supporting SRS switching. FIG. 7 is a diagram of a transmission occurring within a subframe during an SRS switch operation. FIG. 7 is another diagram of a transmission occurring within a subframe during an SRS switching operation. FIG. 8 is yet another diagram of transmissions occurring within a subframe during an SRS switch operation. FIG. 8 is yet another diagram of transmissions occurring within a subframe during an SRS switch operation. FIG. 8 is yet another diagram of transmissions occurring within a subframe during an SRS switch operation. FIG. 6 is a diagram of an example wireless network for supporting carrier aggregation and/or carrier selection. FIG. 6 is a diagram of an example heterogeneous (Het-Net) for supporting carrier aggregation and/or carrier selection. FIG. 8 is a Het-Net diagram of another embodiment for supporting carrier aggregation and/or carrier selection. 6 is a flow chart of an example method for performing synchronization and measurement using a reference signal. FIG. 5 is a diagram of a carrier-based SRS switching scheme. FIG. 6 is a diagram of an SRS switching scheme based on another carrier. FIG. 6 is a diagram of a plurality of SRS switching operations and SRS transmissions of an embodiment in one subframe. It is a figure of the SRS switching system based on another carrier. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. Examples of SRS switching operations with different subframe types and RF architectures are given. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. It is a figure of the SRS switching system based on another carrier. The figure of the processing system of an example is shown. 1 shows a diagram of an example transceiver.

In particular, the propagation delay between UE 210 and base station 220 may be different than the propagation delay between UE 210 and base station 230. Therefore, uplink transmission on component carriers 1566,1567,1569 are uplink transmission with different timing advance (timing advance, TA) of the above component carrier 1541,1542,1545 may require adjustment. Generally, the initial uplink TA adjustment value is determined by a random access procedure. In particular, the UE 210 generally sends a random access preamble to the base stations 220, 230, which then estimate their respective TA values based on the propagation delay associated with the random access preamble and specify the TA value. The corresponding corresponding random access response (RAR) is sent to the UE 210. The UE 210 then uses the initial TA value to send the SRS symbols and other data on the PUCCH and/or PUSCH, and the base stations 220, 230 are based on the propagation delay measured according to the SRS symbols, and the TA The value is constantly updated.

Since the duration of the uplink/downlink RF frequency alignment delay of the UE affects the timing of uplink and downlink transmission on the target component carrier, the UE notifies the base station of these RF frequency alignment delays. May be useful, or even necessary. Embodiments of this disclosure provide a low-overhead frame format for signaling UE uplink/downlink RF frequency alignment delay. FIG. 19 is a diagram of a frame format of an uplink control message 1901 for signaling the uplink and downlink RF frequency alignment delay of the UE. The uplink control message 1901 includes an uplink RF frequency adjustment delay field 1910 and a flag field 1920 . The uplink RF frequency alignment delay field 1910 may be composed of two or more bits indicating the duration of the uplink RF frequency alignment delay of the UE. The bits may represent the duration of the uplink RF frequency alignment delay of the UE as a fraction of the OFDM symbol duration, for example, 0 symbol duration, 0.5 symbol duration, 1 symbol duration, 1.5 symbol duration, etc. .. Flag field 1 920, downlink RF frequency matching the delay of the UE, or is set to a first value indicating that equal to the uplink RF frequency matching delay indicated by field 1910, or downlink RF frequency alignment UE It may consist of a single bit set to a second value indicating that the delay is equal to 0 (otherwise below a lower threshold).

FIG. 22 shows an example communication sequence 2200 for adapting a periodic SRS switching schedule in response to component carrier deactivation. In this example, UE 210 is instructed to periodically transmit SRS symbols on component carriers 2241, 2242, 2243 in aggregated component carrier set 2240 . Therefore, UE 210 periodically transmits SRS symbols 2261-2268 on component carriers 2241, 2242, 2243 during the first set of periods. At some point before the duration of the SRS switch schedule expires, the UE 210 receives a deactivate component carrier message 1222 indicating that the component carrier 2242 is deactivated. The UE 210 is pre-configured to adapt the SRS switching schedule to compensate for the deactivation of the component carrier 2242, so that the UE 210 may not be on the deactivated component carrier 2242 during the second set of periods. Therefore, no SRS symbol is transmitted, and SRS symbols 2271-2283 are transmitted on the component carriers 2241 and 2243 during the setting of the second period.

In some embodiments, uplink RF frequency alignment delay may be experienced during SRS switching. FIG. 33 is a diagram of an uplink transmission that occurs during an SRS switching operation. In this example, the TX chain 218 of UE 210 is used to transmit the uplink signal 3320 on the source component carrier and the SRS symbol 3332 on the target component carrier. UE 210 experiences an uplink RF frequency alignment delay with a duration equal to period t9. Uplink signal 3320 carries SRS symbols 3322. The transmission characteristics of the SRS symbol 3322, such as the transmission power level, may be based on the characteristics of PUSCH/PUCCH signaling in the uplink signal 3320. The transmission characteristics of SRS symbol 3332 may be independent of PUSCH/PUCCH signaling.

FIG. 37 is a diagram of transmissions that occur within subframe 3700 during an SRS switch operation. In this example, the TX chain 218 of UE 210 is used to transmit both the uplink signal 3714 on the source component carrier and the SRS symbol 3722 on the target component carrier. Therefore, the TX chain 218 is switched from the source component carrier to the target component in the middle of transmission of the uplink signal 3714 and the SRS symbol 3722. When the RF frequency matching the delay of the TX chain 218 has a duration not zero, since the guard interval between the downlink portion 3710 of the uplink portion 3720 and the sub-frame 3700 of the sub-frame 3700 does not exist, TX chain 218, It may start its transition to the target component carrier prior to the start of the SRS symbol on the target CC. As a result, the uplink portion 3720 is shortened/punctured in the portion overlapping the UL RF frequency alignment time and SRS transmission.

Some general behavioral designs are discussed. For ease of discussion, these are categorized into three levels:
Carrier level setting for SRS and carrier level for switching from one carrier to another,
Subframe level regarding on which subframe SRS switching and transmission should be performed and the relationship with other transmissions on that subframe, and
Symbol level for SRS switching symbols and transmission symbols. FIG. 40 shows a switching method based on the SRS carrier of the embodiment. As shown, the SRS switching is performed at the carrier level, subframe level and symbol level, and D/S/U represents downlink/special/uplink subframe, respectively.

It should be noted that switching for SRS transmission in UL can cause DL interruption. The DL break may be due to RF frequency tuning in UL switching, in which case the DL break caused by UL frequency tuning is no longer than the RF frequency tuning time (eg, 2 symbols). This may be the case if the UE has a single RFIC or an implementation with strongly coupled transmit and receive chains. DL interruption due to UL tuning may occur if the UE reports that an interruption is required for CA operation (eg CA activation/deactivation etc.), otherwise UL tuning DL interruption by does not occur. Alternatively, it may be the RF tuning time and the UE capability reported to the network, which reflects whether DL interruptions occur during RF tuning. For SRS transmission on the target carrier, DL may also be interrupted during transmission if the UE cannot receive and transmit at the same time in the aggregated cell. As occurs in the blank portion of mbsf N sub frames, DL symbols or subframes interrupted needs to be processed. If there are multiple possibilities of which carrier is suspended in DL, it is necessary to specify the DL carrier of suspension. The suspended DL carrier may be considered as a switching source CC for SRS switching. For example, if switching occurs within subframe n, subframe n+1 is affected, and subframe n+1 is a DL subframe, then either CC1 or CC2 is selected as the affected DL subframe. May be done. The network can set or dictate which should be selected.

FIG. 44A shows a case where the UE switches from CC2 to CC1 for SRS transmission on CC1 in the SRS subframe. Both carriers are special subframes. The UE is assumed to have a single RF design, which combines transmission and reception on CC. It is also assumed that the special subframe settings are consistent, that is, the DwPTS and UpPTS durations are the same for CC. In this case, the UE needs to monitor the DwPTS in the DL, and starts switching after the DwPTS ends. However, if the UE does not detect the PDSCH scheduled for the subframe, the switching may be started immediately after the control region ends. For example, if the control region has 2 symbols but the DwPTS has 3 symbols, the UE does not detect any grant for PDSCH and if it recognizes that it needs to switch to CC1, the second You may start switching from the symbol (counting from 0). However, the DwPTS may include more CRS after the control region. In conventional systems, the UE may or may not monitor these CRSs in the absence of PDSCH. This may be retained, but a better way may be to allow the UE not to monitor these CRSs so that the switching can occur earlier in time. Even if the DwPTS has, for example, 9 symbols, the network may configure the UE to send the SRS on symbol 4 of CC1, while the control region is symbols 0 and 1. Across, the UE needs two symbols to switch. This means that the UE should not assume PDSCH grant and can ignore all CRS after the control region, but switch to CC1 immediately after the control region. Another alternative is that if the UE is configured to send SRS on CC1 on a sufficiently early symbol (e.g. symbol 4), the UE does not include a grant for that subframe to detect, It may be assumed that the CRS on CC2 also need not be monitored. In that case, the eNB does not send any information to be received in the subframe to the UE. There may also be cases where the eNB sends out an aperiodic SRS trigger in a few subframes before the UE schedules SRS transmissions on CC1 and the UE may behave similarly. If the same subframe trigger is used, the UE should detect the PDCCH in the control region, if such a trigger is found, no other DL reception is assumed and the UE moves away from CC2. You can switch immediately. The UE since it is present a certain time to detect the PDCCH seeking trigger, eNB on symbol too early to UE sends is to be noted that shall not trigger the SRS transmission Is. For example, if the control region has two symbols and the UE takes one symbol time to detect and decode the PDCCH (if UE capabilities are known to the network), the fastest switch occurs at symbol 3. , And a faster SRS transmission can occur with symbol 5 on CC1. After the switching, the UE may start SRS transmission for each setting and instruction including the symbol position. It should be noted that there may (or may not) be a gap in the symbol prior to the signaled SRS transmission. There may be one or more SRS transmissions on CC1, and the UE is signaled to switch to another CC for SRS transmission if there is sufficient time left in the subframe. May be. Finally, the UE may be scheduled to transmit the SRS within the UpPTS on CC2 (on one or more symbols), so the UE switches back to CC2 and transmits. Similar concepts and procedures can be adopted if carrier switching is also performed to support RACH transmissions.

In FIG. 44C, the same settings are assumed as in FIG. 44A , except that the UE is assumed to have separate/separate transmit and receive RF designs, whereby the UE is not scheduled for UL on CC2. As long as you can freely switch the transmission from CC2 to CC1. Therefore, in the figure, the UE still receives the DL for the entire DwPTS, but the UL is switched to CC1 even before the DwPTS ends. If the UE recognizes that SRS switching should occur in this subframe, the UE may switch UL even earlier. For example, if SRS transmission on CC1 is configured, the UE can switch even before the subframe starts. In another example, the DwPTS region may span 10 symbols, but the UE detects the trigger for SRS transmission based on the PDCCH in symbols 0 and 1 and detects the DCI in symbol 2 and The decoding can be completed and then switching can be started on symbol 3 while DL reception is still in progress to symbol 9. However, in this case the UE needs to report its RF capabilities, such as being able to receive and transmit at the same time in the aggregated cell.

FIG. 44D shows an example similar to FIG. 44C , but with different special subframe settings for CC. Similar embodiments can be employed.

Example before mentioned, the true whenever appropriate, any of these combinations is performed.

Suppose the SRS trigger is sent in DCI in subframe n. If DL grant is also present in subframe n, then both PDSCH ACK/NACK and SRS need to be sent in subframe n+k, which can cause collisions. If there is a UL grant in subframe n, UL transmission shall also occur in subframe n+k and other collisions shall occur. Either new HARQ timing is introduced or reused for interruption due to measurement gap or SCell activation.

Claims (99)

A method for transmitting a reference signal, comprising:
User equipment (UE) receiving one or more downlink transmissions on a first aggregated component carrier set, the UE in the first aggregated component carrier set The steps of simultaneously transmitting uplink signals on less than all component carriers,
Transmitting, by the UE, sounding reference signal (SRS) symbols on different component carriers in the first aggregated component carrier set during different periods of time. Transmitting the SRS symbols on the different component carriers,
Receiving a radio resource control (RRC) message from a base station by the UE before transmitting the one or more SRS symbols on a first component carrier in the set of aggregate component carriers, An RRC message specifies periodic SRS configuration parameters for transmitting the one or more SRS symbols on the first component carrier, and
Periodically transmitting the one or more SRS symbols on the first component carrier during a periodic interval within a sequence of periodic intervals according to the periodic SRS configuration parameter specified by the RRC message; The method of claim 1, comprising: The method of claim 2, wherein the RRC message specifies a period between consecutive intervals in the sequence of periodic intervals. The RRC message specifies an orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbol position in which the one or more SRS symbols should be transmitted on the component carrier. The method described in. Transmitting the SRS symbols on the different component carriers,
Receiving a downlink control information (DCI) message from a base station before transmitting one or more SRS symbols on a first component carrier in the set of aggregate component carriers, the DCI message comprising: Specifying SRS configuration parameters for transmitting the one or more SRS symbols on the first component carrier;
Aperiodically transmitting the one or more SRS symbols on the first component carrier according to the SRS configuration parameter specified by the DCI message. The method of claim 5, wherein the DCI message specifies a transmit power level for the one or more SRS symbols. 7. The method of claim 5 or 6, wherein the DCI message triggers the aperiodic transmission of the one or more SRS symbols on the first component carrier. The DCI message is received on a second component carrier different from the first component carrier, and the DCI message is received on the second component carrier by the first component carrier on the first component carrier. 8. A method according to any one of claims 5 to 7, which triggers inter-carrier transmission of one or more SRS symbols. The UE receives the DCI message on a primary component carrier of the UE and the one or more SRS symbols are transmitted on a secondary component carrier of the UE. The method described in the section. The method according to any one of claims 5 to 9, wherein the UE receives the DCI message on a common search space of a physical downlink control channel (PDCCH) of the UE. 11. The method according to any one of claims 5 to 10, wherein the DCI message has a DCI length equal to that associated with DCI format 0. From the base station, the RRC message further comprises the step of specifying a downlink control information (DCI) message format for signaling SRS configuration parameters on the physical downlink control channel (PDCCH),
The step of transmitting the SRS symbol monitors the PDCCH for a DCI message having the DCI message format specified by the RRC message, and by the DCI message having the DCI message format specified by the RRC message. The method of claim 1, comprising transmitting one or more SRS symbols on a first component carrier in the first aggregated component carrier set according to the signaled SRS configuration parameter. 13. The method of claim 12, wherein the RRC message specifies a particular DCI message format for indicating SRS transmit power level. 14. The method of claim 12 or 13, wherein the RRC message specifies a particular DCI message format for triggering aperiodic SRS symbol transmission. The method according to any one of claims 12 to 14, wherein the RRC message specifies a specific DCI message format for triggering inter-carrier transmission of SRS symbols. The method according to any one of claims 1 to 15, further comprising the step of transmitting, by the UE, an uplink control message indicating an uplink carrier aggregation capability of the UE. Receiving a downlink control signal that specifies a dual connectivity cell group configuration constraint from a network controller, wherein the dual connectivity cell group configuration constraint is: (i) the UE, during the set period, a first Switching from a source component carrier in the first aggregated component carrier set monitored by a base station to a target component carrier in a second aggregated component carrier set monitored by a second base station. And (ii) the UE from a source component carrier in the second aggregated component carrier set monitored by the second base station during the set of time periods, The method of claim 1, further comprising the steps of both prohibiting switching to a target component carrier in the first aggregated component carrier set monitored by a first base station. .. The step of transmitting the SRS symbol comprises:
Use the first transmit chain (TX chain) of the UE to transmit any SRS symbol on a component carrier in the second aggregated component carrier during any period in the set of periods Without transmitting at least a first SRS symbol on a different component carrier in the set of first aggregated component carriers during a different period in the set of periods via the first TX chain Steps,
Not using the second TX chain of the UE to transmit any SRS symbol on a component carrier in the second aggregated component carrier during any period in the set of periods, Transmitting at least a second SRS symbol on a different component carrier in the second aggregated component carrier during a different period in the set of periods via the second TX chain; 18. The method of claim 17, comprising. Receiving, by the UE, a higher layer control signal from a network controller, the higher layer control signal being, for the UE, a component carrier in the first aggregated component carrier set according to a periodic interval. 7. The method of claim 1, further comprising: specifying a periodic uplink SRS switch setting that commands switching between. The step of transmitting the SRS symbol comprises:
Transmitting at least one SRS symbol on each component carrier in the aggregated set of component carriers according to the periodic uplink SRS switching setting during a first set of periods;
Receiving, by the UE, a Medium Access Control (MAC) message from the network controller, the MAC message deactivating at least one component carrier in the aggregated set of component carriers; ,
Not transmitting any SRS symbols on the at least one deactivated component carrier during the second set of periods and according to the periodic uplink SRS switch setting during the second set of periods, Transmitting at least one SRS symbol on each of the remaining component carriers in the aggregated set of component carriers. Receiving a single downlink control message and at least a first field, the single downlink control message comprising a plurality of SRS commands for a plurality of UEs, and
Identifying the position of an SRS command for the UE among the plurality of SRS commands in the single downlink control message based on the number of bits indicated by the field. The method according to 1. 22. The method of claim 21, wherein the first field is a field in the single downlink control message. 23. The method of claim 21 or 22, wherein the first field is received via higher layer signaling. 24. The method of any of claims 21-23, wherein the SRS command indicates a transmit power level to be used when transmitting SRS symbols. The method according to any one of claims 21 to 24, wherein the SRS command indicates a condition for triggering an aperiodic SRS symbol transmission. The method of claim 1, wherein the one or more downlink transmissions are transmitted by a single base station. The one or more downlink transmissions include at least a first downlink transmission on the first component carrier and a second downlink transmission on the second component carrier, and 27. The method of claim 26, wherein the downlink transmission and the second downlink transmission are transmitted by the same or different base stations during a common period. 28. The method of claim 27, wherein the first downlink transmission corresponds to a primary cell and the second downlink transmission corresponds to a secondary cell. 28. The method of claim 27, wherein the first downlink transmission corresponds to a different secondary cell than the second downlink transmission. A method for receiving a reference signal, comprising:
A step of transmitting, by a first base station, one or more downlink signals to a user equipment (UE) on a first aggregated set of component carriers, the UE being the first aggregated The uplink signal cannot be transmitted simultaneously on all component carriers in the set of component carriers,
Receiving by a base station a Sounding Reference Signal (SRS) symbol from the UE on a different component carrier in a first aggregated component carrier set during a different time period. Transmitting a radio resource control (RRC) message to the UE by the first base station, the RRC message for transmitting the one or more SRS symbols on the first component carrier. The step of specifying the periodic SRS configuration parameters,
The one or more SRS symbols on the first component carrier during a periodic interval within a sequence of periodic intervals according to the periodic SRS configuration parameter specified by the RRC message by the first base station. 31. The method of claim 30, further comprising: 32. The method of claim 31, wherein the RRC message specifies a period between consecutive intervals in the sequence of periodic intervals. 32. The RRC message specifies orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbol positions in which the one or more SRS symbols should be transmitted on the component carrier. Or the method described in 32. Transmitting a downlink control information (DCI) message to the UE by the first base station, wherein the DCI message is an SRS for transmitting one or more SRS symbols on a first component carrier. A step to specify the configuration parameters,
Receiving a SRS symbol from the UE on a first component carrier during a first period by the first base station, the SRS symbol according to the SRS configuration parameter specified by the DCI message. 31. The method of claim 30, further comprising: being transmitted. The method of claim 34, wherein the DCI message specifies a transmit power level for the SRS symbols. The method of claim 34, wherein the DCI message triggers aperiodic transmission of the SRS symbols. The DCI message is received on a second component carrier different from the first component carrier, and the DCI message is received on the second component carrier by the SRS on the first component carrier. 37. A method according to any one of claims 34 to 36, which triggers inter-carrier transmission of symbols. The step of transmitting a radio resource control (RRC) message to the UE by the first base station, wherein the RRC message is a downlink control information (DCI) format for indicating a sounding reference signal (SRS) setting parameter. Specify the step and
Transmitting a DCI message with the DCI format to the UE by the first base station;
The first base station, after transmitting the DCI message having the DCI format to the UE, is a step of receiving an SRS symbol from the UE, the DCI message, for the UE, the SRS configuration 31. Instructing to transmit the SRS symbol according to a parameter, the method further comprising: 39. The method of claim 38, wherein the RRC message specifies a particular DCI message format to indicate SRS transmit power level. 39. The method of claim 38, wherein the RRC message specifies a particular DCI message format for triggering aperiodic SRS symbol transmission. 39. The method of claim 38, wherein the RRC message specifies a particular DCI message format for triggering inter-carrier transmission of SRS symbols. The first base station is a step of receiving an uplink control message from the UE, the uplink control message indicates the uplink carrier aggregation capability of the UE, a step,
By the first base station, based on the carrier aggregation capability of the UE, assigning an uplink carrier switching setting to the UE,
The first base station is a step of sending a downlink control signal to the UE, the downlink control signal, for the UE, based on the uplink carrier switching setting, aggregated component carrier 31. The method of claim 30, further comprising instructing to transmit the SRS symbols on the set of. The uplink carrier switching setting is at least a first component carrier assigned to carry the SRS symbol and physical uplink control channel/physical uplink shared channel (PUCCH/PUSCH) transmission of the UE, and the UE 43. The method of claim 42, wherein the method does not carry PUCCH/PUSCH transmissions and specifies at least a second component carrier assigned to carry sounding reference signal (SRS) symbol transmissions for the UE. The uplink carrier switching setting is, for the UE, at least one of a first SRS symbol and a PUSCH or PUCCH signal on the first component carrier during an initial period, and after the initial period is continued. 44. The method of claim 43, instructing to transmit a second SRS symbol on the second component carrier during a time period. 43. The method of claim 42, wherein the uplink carrier switch setting specifies a periodic interval for switching from a source component carrier to a target component carrier. Transmitting a downlink control signal designating a dual connectivity cell group configuration constraint to the UE, the first aggregated set of component carriers being at least a first monitored by a first base station. A set of aggregated component carriers of, and a second aggregated set of component carriers monitored by a second base station, wherein the dual connectivity cell group configuration constraint is (i) the UE: Prohibiting switching from a source component carrier in the first aggregated component carrier set to a target component carrier in the second aggregated component carrier set during a set of time periods; ii) The UE switches from a source component carrier in the second aggregated component carrier set to a target component carrier in the second aggregated component carrier set during the set of time periods. 31. The method of claim 30, further comprising the step of both prohibiting. The step of receiving an uplink control message from the UE by the first base station, wherein the uplink control message is an uplink radio frequency (RF) of the UE for switching from a source component carrier to a target component carrier. Two or more bits indicating frequency adjustment delay and a first value indicating that the downlink frequency adjustment delay of the UE is equal to the uplink frequency adjustment delay of the UE, or the downlink frequency adjustment delay of the UE A single bit set to any of the second values when is equal to 0,
By the first base station, based on the downlink frequency alignment delay of the UE, assigning an uplink carrier switching setting to the UE,
The step of transmitting a downlink control signal to the UE by the first base station, wherein the downlink control signal is first aggregated with respect to the UE based on the uplink carrier switching setting. 31. Instructing to transmit the SRS symbol on a set of different component carriers, the method of claim 30, further comprising: The uplink control message indicates a specific uplink frequency alignment delay for switching from a first RF band that includes the source component carrier to a second RF band that includes the target component carrier. the method of. 49. The method of claim 48, wherein the first RF band is different than the second RF band. The two or more bits of the uplink control message indicate the uplink RF frequency alignment delay of the UE as a number of orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbols, 49. The method of claim 48. A single downlink control message to both the first UE and the second UE by the base station, a first field to the first UE and a second field to the second UE. And a single downlink control message carrying a first SRS command for the first UE and a second SRS command for the second UE, The first field indicates a number of bits used to indicate the first SRS command in the single downlink control message, and the second field indicates the single downlink control message. 31. The method of claim 30, further comprising the step of indicating a number of bits used to indicate the second SRS instruction in. 52. The method of claim 51, wherein the first field and the second field are fields within the single downlink control message. 52. The method of claim 51, wherein the first field and the second field are transmitted to the first UE and the second UE, respectively, via higher layer signaling. The first SRS command and the second SRS command indicate transmission power levels used by the first UE and the second UE, respectively, when transmitting SRS symbols. The method according to any one of the above. 54. The first SRS command and the second SRS command indicate SRS trigger conditions for triggering SRS symbol transmission by the first UE and the second UE, respectively, any one of claims 51 to 53. The method according to item 1. A step of transmitting a first uplink signal in a first subframe on a first component carrier by a user apparatus (UE) during a first period, wherein the first uplink signal is at least Carrying a first sounding reference signal (SRS) symbol, and
The UE switching from the first component carrier to the second component carrier according to an SRS switching schedule, wherein the uplink RF frequency adjustment delay is switched from the first component carrier to the second component carrier. Steps related to
A step of transmitting, by the UE, a second uplink signal in a second subframe on the second component carrier during a second period, wherein the second uplink signal is the second Carrying at least one of an SRS symbol and a random access preamble. 57. The method of claim 56, further comprising sending an uplink control message by the UE to a base station, the control message specifying a duration of the uplink RF frequency alignment delay. In the uplink control message, two or more bits indicating the duration of the RF frequency adjustment delay of the UE and the downlink RF frequency adjustment delay of the UE are equal to the uplink RF frequency adjustment delay of the UE. 58. A single bit set to either a first value indicating that or a second value indicating that the downlink RF frequency alignment delay of the UE is equal to 0. the method of. The two or more bits of the uplink control message indicate the uplink RF frequency alignment delay of the UE as a number of orthogonal frequency division multiplexing (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbols, The method of claim 57. The UE has a physical downlink control channel on an orthogonal frequency division multiplex (OFDM) or single carrier frequency division multiple access (SC-FDMA) symbol of the second component carrier that overlaps in time with the downlink RF frequency alignment delay. 59. The method of claim 58, which does not monitor or receive (PDCCH) or Physical Downlink Shared Channel (PDSCH). Transmitting the second uplink signal in the second subframe on the second component carrier during the second period,
57. The method of claim 56, comprising puncturing the portion of the second uplink signal that corresponds to the duration of the uplink RF frequency alignment delay. A method for switching a reference signal, comprising:
User equipment (UE) is a step of transmitting a first sounding reference signal (SRS) symbol on a primary component carrier during a first period, said UE on a secondary component carrier during a second period. Of the second SRS symbol and the uplink control message on the primary carrier during the second time period are scheduled to be transmitted, whereby the SRS symbol and the uplink control message are Causing a scheduling conflict between the steps,
When the uplink control message satisfies a criterion by the UE, the second SRS symbol is not transmitted on the secondary component carrier during the second period, and the primary component carrier during the second period. Sending the uplink control message above. 63. The method of claim 62, wherein the uplink control message meets the criteria when the uplink control message includes a positive or negative acknowledgment (ACK/NACK) message. 64. The method of claim 63, wherein the uplink control message meets the criteria when the uplink control message includes channel state information (CSI). 65. A method of transmitting the second SRS symbol on the secondary carrier during a third time period, the third time period further comprising the second time period, further comprising: The method according to any one of items. 66. The method of claim 65, wherein the third time period is the next available opportunity to transmit the second SRS symbol. A step of receiving a control signal from a base station by a user apparatus (UE), the control signal indicating that a set of aggregated component carriers is assigned to a timing advance group (TAG), and assigned to the TAG. At least the first component carrier does not support physical uplink control channel (PUCCH) signaling or physical uplink shared channel (PUSCH) signaling, and
Transmitting a sounding reference signal (SRS) symbol by the UE on one or more component carriers assigned to the TAG according to a timing advance parameter associated with the TAG. Transmitting a random access preamble to a base station by the UE, the RACH message requesting timing advance for the first component carrier, and
Receiving, by the UE, a control signal indicating the timing advance for the first component carrier from the base station;
The UE does not transmit any PUSCH signaling on the first component carrier during a first period, and does not transmit any PUCCH signaling, the first advance during the first period according to the timing advance. 68. The method of claim 67, further comprising: transmitting a first sounding reference signal (SRS) symbol on the component carrier. Transmitting a second SRS symbol on a second component carrier during a second period, the UE transmitting any uplink signaling on the second component carrier during the first period. And transmitting the first SRS symbol on a first component carrier during the first period, the UE does not use any uplink signaling on the first component carrier during the second period. 69. The method of claim 68, further comprising transmitting the second SRS symbol on the second component carrier during the second period without transmitting. The UE does not receive an explicit command to switch from the first component carrier to the second component carrier, and based on a preset SRS switching interval, the second during the second period. 70. The method of claim 69, transmitting the second SRS symbol on two component carriers. The preset SRS switching interval, for the UE, SRS symbols on a subset of different component carriers in the aggregated set of component carriers during different periods within a series of periodically occurring periods. 71. The method of claim 70, wherein the method is a periodic switch interval instructing to transmit. Receiving a switching command from the base station by the UE, the switching command transmitting the second SRS symbol on the second component carrier to the UE during the second period. 70. The method of claim 69, further comprising the step of instructing to: 73. The method of claim 72, wherein the switching command is received in a downlink control information (DCI) message. Transmitting a downlink signal to the user equipment (UE) on the aggregated set of component carriers by the base station,
Receiving by the base station a first sounding reference signal (SRS) symbol from the UE on a first component carrier in the aggregated set of component carriers during a first period;
Receiving, by the base station, a second SRS symbol from the UE on a second component carrier in the aggregated set of component carriers during a second time period, the second component carrier being Different from the first component carrier. The first SRS symbol does not receive any uplink signaling from the UE on the second component carrier during the first period, and on the first component carrier during the first period. Received from the UE, the second SRS symbol does not receive any uplink signaling from the UE on the first component carrier during the second period, and the second SRS symbol during the second period. 75. The method of claim 74, received from the UE on two component carriers. The step of transmitting a switching command to the UE by the base station, wherein the switching command is for the UE to transmit the second SRS symbol on the second component carrier during the second period. 76. The method of claim 74 or 75, further comprising the step of instructing to send. 77. The method according to any one of claims 74 to 76, wherein the first component carrier supports physical uplink shared channel (PUSCH) transmission. 78. The method of claim 77, wherein the second component carrier does not support PUSCH transmission. On the first component carrier during a third period, unless the UE is instructed to transmit the third SRS symbol on a different component carrier that does not support PUSCH and/or PUCCH transmission. 79. The method according to any one of claims 74 to 78, further comprising: transmitting at least one of the third SRS symbol, PUSCH and PUCCH at. 79. The first component carrier is frequency division duplex (FDD) and the second component carrier is time division duplex (TDD) or in an unpaired spectrum. The method according to any one of the items. 79. The method of any of claims 74-78, wherein both the first component carrier and the second component carrier are Time Division Duplex (TDD) or in an unpaired spectrum. .. A step of receiving a first downlink transmission on the first component carrier and a second downlink transmission on the second component carrier, for the first downlink transmission Transmission parameters are derived from received signal information corresponding to the first SRS symbols, and transmission parameters for the second downlink transmission are derived from received signal information corresponding to the second SRS symbols. 82. The method according to any one of claims 74 to 81, further comprising: The UE does not transmit any Physical Uplink Shared Channel (PUSCH) signaling on the first component carrier during the first period, and on the first component carrier during the first period. 83. The SRS configuration parameter is transmitted on the first component carrier during the first period without transmitting any physical uplink control channel (PUCCH) signaling. the method of. A step of transmitting a control signal to a user equipment (UE) by a base station, wherein the control signal indicates that the aggregated set of component carriers is assigned to a timing advance group (TAG), and is assigned to the TAG. And at least one component carrier does not support physical uplink control channel (PUCCH) signaling and physical uplink shared channel (PUSCH) signaling, and the control signal indicates to the UE the timing advance associated with the TAG. A method comprising: prompting to transmit a Sounding Reference Signal (SRS) symbol on one or more component carriers assigned to the TAG according to a parameter. 85. The method of claim 84, wherein the control signal is a downlink control information (DCI) message. 85. The method of claim 84, further comprising receiving by the base station at least one of a Random Access Channel (RACH) message and an SRS symbol on a secondary component carrier that does not carry PUCCH or PUSCH transmissions of the UE. .. 87. The method of claim 86, wherein the RACH message is sent on a non-contention based access channel. 88. The method of claim 87, wherein both the RACH message and the SRS symbol are received on the secondary component carrier. By the base station, before receiving the RACH message and / or the SRS symbol on the secondary component carrier, is a step of receiving PUCCH or PUSCH transmission from the UE on the primary component, the UE, the primary 89. The method of claim 87, further comprising switching from the primary component carrier to the secondary component carrier after sending the PUCCH or PUSCH transmission on a component carrier. The base station is a step of transmitting a downlink control command (DCI) message to the UE, the DCI message commands the UE to switch from the primary component carrier to the secondary component carrier, 90. The method of claim 89, further comprising steps. A step of receiving a random access channel (RACH) transmission from a user equipment (UE) by a base station, said RACH transmission not requesting permission for a physical uplink control channel (PUCCH) resource, and a physical uplink Requesting timing advance for component carriers without requesting grants for link shared channel (PUSCH) resources, and
By the base station, transmitting to the UE a control signal indicating the timing advance for the component carrier,
The base station does not receive any PUSCH signaling on the component carrier, and does not receive any PUCCH signaling on the component carrier, and according to the timing advance, one or more soundings from the UE on the component carrier. Receiving a reference signal (SRS) symbol. A method for transmitting a reference signal, comprising:
Reporting the component carrier capabilities of the user equipment (UE) to the base station,
Configuring the UE based on information from the base station for a first set of component carriers for one or more downlink receptions;
The first component carrier for one or more uplink transmissions including at least one of a physical uplink control channel (PUCCH), a physical uplink shared channel (PUSCH) or a sounding reference signal (SRS) symbol transmission. Configuring the UE based on information from the base station for a subset of first component carriers in the set of, the UE on all component carriers in the first subset of component carriers. With the step that can transmit the uplink signal at the same time,
The eNB for the second subset of component carriers within the first set of component carriers for one or more SRS transmissions without configuring the second subset of component carriers for PUSCH/PUCCH transmission. Configuring the UE based on information from
Transmitting, by the UE, SRS symbols on different component carriers within the first subset of component carriers and the second subset of component carriers during different periods of time. 93. The method of claim 92, wherein the number of component carriers in the first subset of component carriers and the second subset of component carriers exceeds the indicated uplink carrier aggregation capability of the UE. 94. The method of claim 93, wherein the number of component carriers in the second subset of component carriers exceeds the indicated uplink carrier aggregation capability of the UE. A step of transmitting a first uplink signal on a first component carrier during a first period by a user apparatus (UE), the first uplink signal being at least a first sounding reference signal ( SRS) carrying symbols,
Switching by the UE from the first component carrier to a second component carrier according to a switching parameter for an SRS switching schedule;
The UE transmits a second uplink signal on the second component carrier during a second period, the second uplink signal comprising a second SRS symbol and a random access preamble. Carrying at least one of the above, wherein said transmission occurs after an uplink RF frequency tuning time. 96. The method of claim 95, wherein the switching parameter is determined by a setting received before the first time period. 96. The method of claim 95, wherein the switching parameter is determined by messaging received during the first time period. A method for transmitting a reference signal, comprising:
Receiving one or more downlink transmissions on a set of aggregated component carriers by a user equipment (UE),
At least one of the first Sounding Reference Signal (SRS) symbols and the physical uplink shared channel (on the first component carrier in the aggregated set of component carriers during the first period by the UE). PUSCH) signal and at least one of physical uplink control channel (PUCCH) signaling, wherein at least one of the parameters for the SRS symbol is generated based on the parameters for the PUSCH. Step,
The UE does not send any PUSCH signal and PUCCH signaling on a second component carrier during a second time period, and the second component in the aggregated set of component carriers during the second time period. Transmitting at least a second SRS symbol on a carrier, wherein the second component carrier is different from the first component carrier and none of the parameters for the SRS symbol is for any PUSCH. And a step that is not generated based on the parameters of. A step of receiving a control signal from a base station by the user apparatus (UE), the control signal indicating that the second component carrier is assigned to a timing advance group (TAG), and
100. further comprising: by the UE, transmitting sounding reference signal (SRS) symbols on one or more component carriers assigned to the TAG according to a timing advance parameter associated with the TAG. Method.

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